How the Royal Navy Outsmarted Nazi U-Boats - The Secret Tactics That Won the Atlantic

[00:00:03]Britain is at the mercy of Dönitz's U-boats.

[00:00:08]The Royal Navy pinned their hopes on a tactic to fight back.

[00:00:11]>> Hard a cover stern.

[00:00:15]>> Good. At least one U-boat down.

[00:00:17]>> Prove they attack from outside the convoy.

[00:00:20]>> But war gamer Gilbert Roberts >> Is something wrong?

[00:00:23]>> and a team of Wrens discover it doesn't make sense.

[00:00:28]>> The Royal Navy are relying on luck to protect the convoys.

[00:00:31]>> Mein Führer, we are strangling the life out of Britain. I can strike a decisive blow, but I need more U-boats.

[00:00:40]>> Dönitz floods the Atlantic with monster wolf packs.

[00:00:44]>> Fire!

[00:00:49]>> Imagine the carnage we will sow.

[00:00:55]>> Some people look out at the ocean and see tranquility.

[00:01:01]It's not tranquil.

[00:01:03]It will devour you.

[00:01:06]>> Roberts is in a race against time to decipher the U-boat tactics.

[00:01:12]>> U-boat destroyed.

[00:01:14]>> It works.

[00:01:15]>> Run the game again.

[00:01:17]We need to be sure.

[00:01:18]>> Then convince the top brass to change their ways.

[00:01:22]>> Why am I here, Commander?

[00:01:25]We can't keep losing men and convoys to the sea and Dönitz. We have to make the Admiralty listen.

[00:01:32]Their survival and ours depends on it.

[00:01:52]>> Gilbert Roberts and the Wrens team have worked deep into the night. All this time, the Royal Navy has assumed that the U-boats are firing the torpedoes from outside the convoy into the center of it.

[00:02:04]>> By analyzing the use of Walker's Buttercup tactic, they've discovered that the U-boats are already inside the convoy when they're making their initial attack.

[00:02:17]>> If everything that the Royal Navy has assumed about the way U-boats attack is wrong, this means their defense [music] strategy is wrong.

[00:02:26]>> The SS Andover was hit in the center of the convoy.

[00:02:32]The U-boats must be attacking from the inside. [music] >> But how is Dönitz getting them there?

[00:02:40]We need to think like a U-boat captain.

[00:02:44]How would you get in?

[00:02:48]>> Commander Walker did sink a U-boat at the rear.

[00:02:53]Could they sneak in submerged from the stern?

[00:02:58]>> Convoy travels at roughly seven knots.

[00:03:01]Submerged, the U-boat has to rely on its electric motors, and they're slow. Can only do >> eight knots. So, unlikely one could catch and enter a convoy and not be pinged by asdic.

[00:03:17]How about from the front?

[00:03:22]>> They could enter from ahead, submerged, but coming straight at the convoy.

[00:03:32]There's a big risk of a collision.

[00:03:43]>> On the surface, a U-boat can use its diesel motors.

[00:03:48]A Type 7C can run at 17 knots.

[00:03:51]It's much faster than the convoy. It's more like a motor torpedo boat.

[00:03:58]>> So, they could be infiltrating the convoy from behind.

[00:04:03]And on the surface >> They're fast enough.

[00:04:06]>> And the lookouts rarely look behind them.

[00:04:09]>> If they came in at night, they wouldn't be seen.

[00:04:12]>> Staring.

[00:04:14]Ruthless. I wouldn't put it past him.

[00:04:18]>> Walker did sink a U-boat astern traveling the same course as the convoy.

[00:04:22]>> Could it have been caught trying to go into the convoy?

[00:04:25]>> Sneaking in on the surface.

[00:04:28]>> That's it.

[00:04:30]Must be.

[00:04:35]What is it?

[00:04:37]>> Once inside, [music] they torpedo a ship, many ships. Now, every destroyer is looking for them.

[00:04:45]So, then how does the actual attacker get out?

[00:04:56]>> We've been at this a while.

[00:04:58]Let's break and come back with fresh eyes.

[00:05:16]>> How are the sandwiches?

[00:05:19]Could do with some more.

[00:05:20]>> Corn beef.

[00:05:23]How's the coffee?

[00:05:25]>> Could do with some more coffee.

[00:05:28]>> Rationing, I guess.

[00:05:33]I just wish I could see how the U-boats escape.

[00:05:39]>> Even if you could, you think the admirals would listen?

[00:05:43]>> What do you think, sir?

[00:05:45]Will the top brass even listen to us?

[00:05:49]So.

[00:05:51]>> Sorry, Nela.

[00:05:53]I was in a world of my own.

[00:05:56]>> You're very quiet, sir.

[00:05:57]>> Yes, quiet. Sorry.

[00:05:59]I seem to have a lot on my Quiet.

[00:06:07]Could that be it?

[00:06:09]>> Quiet.

[00:06:14]>> Finish up.

[00:06:16]We need to go back to the board.

[00:06:19]The U-boat launches its attack.

[00:06:22]But after it fires, it needs to escape.

[00:06:25]Where does it go?

[00:06:27]>> The escorts are firing flares. The sea is lit up. The U-boat is surrounded by convoy ships. Any one of those could spot it and raise the alarm.

[00:06:38]The logical thing to do is dive.

[00:06:45]Gone.

[00:06:47]How deep can they go?

[00:06:48]A Type 7C.

[00:06:50]720 ft.

[00:06:52]>> On the edge of effective asdic range.

[00:06:55]>> Then they stop.

[00:06:57]They go quiet. [music] And they wait for the convoy to pass over them.

[00:07:03]Once the convoy moves on, they surface [music] again.

[00:07:12]What if the escorts are away from the convoy?

[00:07:14]>> Yes.

[00:07:16]The U-boat can surface safely because thanks to Walker's buttercup tactic, the escorts search away from the convoy and then continue moving with it.

[00:07:26]>> They're looking in the wrong place.

[00:07:29]>> Walker must have hit a U-boat trying to get into the convoy.

[00:07:33]That's why buttercup can't be easily repeated.

[00:07:37]>> This is an incredible breakthrough. The Royal Navy assumes that the U-boats attack from outside the convoys [music] and they can't see past this assumption.

[00:07:46]>> But the fact that these Wrens weren't Navy indoctrinated people meant that they were able to take the bare minimum facts, [music] strategize it, work out the tactics, and put themselves in the mind of the [music] enemy.

[00:08:01]>> We need to run the game.

[00:08:12]>> Admiral Karl Dönitz, his tonnage war is working.

[00:08:17]>> Herr Admiral, a report [music] from U-504 operating in the Straits of Florida.

[00:08:28]>> Single large ships at night within 200-m line.

[00:08:32]Moderate destroyer and air patrols since first attack.

[00:08:36]Good chances for attack, but strong patrolling in DB9790.

[00:08:45]They've sunk three ships already.

[00:08:49]Two of them tankers.

[00:08:55]>> [music] >> Send a reply to U-128, 129, and 504. Occupy attack square DB90, the Straits of Florida.

[00:09:06]>> Yes, Herr Admiral.

[00:09:11]>> What is our monthly tonnage tally?

[00:09:18]>> Herr Admiral, 70 ships sunk for over 392,000 tons.

[00:09:26]>> Excellent.

[00:09:28]If the fleet keeps sinking this many tons, the Führer will have no choice but to give me my 300 U-boats.

[00:09:36]>> The US Navy weren't or prepared for the onslaught of U-boats against their own coastline. So, in early 1942, they really did not have the escorts to protect the ships.

[00:09:49]>> The U-boat crews certainly were surprised. Perfect targets with no sign of defense or escorts around. As soon as Dönitz noticed that it was so easy to sink vessels, he sent more and more U-boats.

[00:10:08]>> February of 1942, the number of sinkings and the total amount of tonnage destroyed skyrocketed.

[00:10:16]If the ships could not get through, Britain could not feed itself, so literally could be starved to death.

[00:10:27]>> Imagine the carnage we will sow.

[00:10:35]>> Ready?

[00:10:37]Let's begin.

[00:10:39]>> When you're wargaming, [music] if you've identified the enemy's intent and the approach they will use, that is absolutely decisive.

[00:10:48]>> But the question is, how are you going to use it and turn the tables so that the hunters now become the hunted?

[00:10:56]>> Roberts and Laidlaw are now setting [music] up the game, and Roberts is going to play the U-boat commander.

[00:11:03]>> Merchant [music] ship torpedoed. Fifth column, third ship. Time in 0210 hours. Next move in 2 minutes.

[00:11:10]>> And Laidlaw's going to play the escort commander, responsible for finding and sinking the U-boats.

[00:11:17]Around the game room are screens of canvas with a slit [music] cut through the middle and a lens inserted. The U-boat movements are marked in brown chalk on the brown linoleum, which makes it very difficult for the escort commanders to see their patterns of movement.

[00:11:33]>> You'd only see the white chalk of the movements of the convoy and the escorts.

[00:11:45]>> U-boat undetected, U-boat escaped.

[00:11:48]Game over.

[00:11:53]>> [music] >> Let's run the game [music] again.

[00:12:05]>> Merchant ship torpedoed, fifth column third ship. Time in 0232 hours, next move in 2 minutes.

[00:12:14]>> What's interesting about wargaming is you want to win, so you start reaching for different things that you might not otherwise have considered.

[00:12:24]>> Buttercup means that the escort ships sweep outward in a sort of fan-like position. Laidlaw comes up with the idea that if the U-boat is hanging back to the rear and has submerged, she needs to use her escorts in a different [music] way, looking backwards.

[00:12:42]>> Next move 2 minutes.

[00:12:45]>> So, as the convoy moves forward, she has the escorts open up with [music] Aztec sonar to look all over the back in this sort of triangular fashion.

[00:12:56]>> Aztec ping on 130, likely U-boat contact.

[00:13:01]>> Eventually, they're going to pass over it, and when they do, they'll detect it, and then they can send depth charges down and destroy it.

[00:13:12]>> U-boat depth charged, U-boat destroyed.

[00:13:15]>> U-boat destroyed.

[00:13:18]How?

[00:13:24]The escorts fall to the back, Conduct triangular sweeps.

[00:13:29]The retreating U-boat is caught up in them.

[00:13:33]Law.

[00:13:35]Triangular sweeps.

[00:13:37]>> It works.

[00:13:40]>> Run the game again.

[00:13:42]We need to be sure.

[00:13:44]>> So, they play the game again and again.

[00:13:46][music] The escorts at the rear of the convoy are using ASDIC almost like dragging a fishing net through the water.

[00:13:58]The U-boat is going to be caught up in this. They will discover it and they will be able to destroy it.

[00:14:04]>> U-boat depth charged, U-boat destroyed.

[00:14:07]>> As dawn comes, Robertson and Law are completely convinced now that their tactic can't be faulted.

[00:14:17]>> Sir, McAslan here.

[00:14:20]>> Thank you for your work tonight.

[00:14:23]Get some rest.

[00:14:24]>> Yes, sir.

[00:14:25]You too.

[00:14:33]>> Western Approaches command duty officer.

[00:14:37]>> This is Commander Robertson of the Western Approaches tactical unit. Can you take a message for Admiral Noble?

[00:14:42]>> Yes, sir.

[00:14:44]>> W 2 has discovered something of vital importance to U-boat tactics and counter-tactics. Request his attendance here as soon as possible to explain.

[00:14:54]>> Yes, sir. Is that all?

[00:14:56]>> Yes, that is all. Thank you.

[00:15:02]>> Will Admiral Noble listen, sir?

[00:15:11]>> Have you ever seen a man drown, Law?

[00:15:16]I have.

[00:15:18]I was 23.

[00:15:22]He was caught in the current and I dived in after him.

[00:15:27]By the time I got there, it was too late. He He was dead and I had to be fished out myself.

[00:15:36]I'll never forget the look on his face.

[00:15:39]Frozen.

[00:15:42]With all the life gone from him.

[00:15:50]Some people look out at the ocean and see tranquility.

[00:15:56]It's not tranquil.

[00:16:00]It will devour you.

[00:16:05]We can't keep losing men and convoys to the sea and Dönitz. We have to make the Admiralty listen.

[00:16:13]Their survival and ours depends on it.

[00:16:23]>> Dönitz's U-boat fleet is wreaking havoc, particularly against poorly protected American shipping.

[00:16:32]>> The Americans at one point actually had 50 destroyers operating on the transatlantic convoys.

[00:16:37]>> The problem in early '42 is that most of those 50 destroyers the Americans have in the northwest Atlantic have gone off to fight the Japanese.

[00:16:46]>> The great success of the German U-boats off the US East Coast wasn't due to the lack of convoys, the lack of escorts.

[00:16:55]>> Tube one, fire.

[00:17:04]>> Simply the failures of the US Navy to effectively protect their merchant shipping.

[00:17:12]>> The losses to Allied shipping in in the first six, maybe seven months of 1942 are staggering.

[00:17:20]2 million tons are lost. We're talking about 111 ships sunk in May and about 115 ships sunk in June.

[00:17:30]It's an unbelievable tragedy for the allies and an enormous success for the Germans.

[00:17:48]>> Mein Führer, in the Mediterranean Sea and the North Atlantic shipping lanes to Britain, and up and down the East Coast of America, our U-boats are sinking ship after ship.

[00:18:01]We are strangling the life out of Britain.

[00:18:04]Yeah, our monthly tonnage tallies, they rise and rise.

[00:18:23]>> It really is the second happy time, as you U-boat men say.

[00:18:31]>> Indeed, mein Führer, but there is a risk.

[00:18:34]Now that the Americans are also enemies of the Third Reich, they may try to land an army in Europe. Now to do that, they will need to move men and equipment across the Atlantic. It takes 32,000 tons of shipping to move one US division.

[00:18:51]But I can strike a decisive blow so that doesn't happen.

[00:18:55]But I need more U-boats.

[00:19:04]>> Steel is scarce.

[00:19:07]>> This is a question of winning the war.

[00:19:12]>> For Hitler, success was the currency for his value of his leading officers. These successes made Dönitz a very valuable asset in Hitler's mind.

[00:19:28]>> You can have your 300 U-boats, Dönitz, but you must close down the Atlantic.

[00:19:40]>> Once Roberts and Laidlaw have worked out what they think the U-boat strategy is and how they're going to combat it, they've got to convince the top brass. We've already seen how skeptical Noble is of Roberts.

[00:19:55]>> He's always been skeptical of the war gaming. It's imperative that they get Sir Percy Noble to listen to them because ships are being sunk, human beings' lives are being lost at sea.

[00:20:08]>> Commander Roberts.

[00:20:10]Good morning, sir.

[00:20:11]Thank you for coming on such short notice.

[00:20:15]>> Why am I here, Commander?

[00:20:19]>> Sir, we've discovered something of vital importance to U-boat tactics and counter-tactics.

[00:20:24]>> Yes, I read your message to my office.

[00:20:28]>> Sir, we've simulated convoy HG 76 using the war [music] game.

[00:20:33]>> Ah, yes, the war game.

[00:20:37]>> Yes, sir, the war game.

[00:20:40]Echo, would you?

[00:20:42]By simulating this report, we've discovered that the U-boats get inside the convoy and do so at night and on the surface where they're faster.

[00:20:53]Here, they launch their torpedoes and [snorts] after the attack, dive.

[00:21:00]Now, they go quiet and wait.

[00:21:02]As the convoy continues to steam on ahead, they surface well astern and out of danger.

[00:21:10]In the standard anti-submarine tactic Buttercup, the escorts search away from the convoy, outwards. But they're looking for the U-boats in entirely the wrong position.

[00:21:21]>> Roberts, everyone knows that the U-boats fire from outside the convoy in.

[00:21:28]>> So, with respect, I reached this conclusion after consulting Admiral Horton at Flag Office Submarines.

[00:21:36]>> Max Horton is the leading submariner in Great Britain. If anyone understands the thinking of the enemy, it's Max Horton.

[00:21:47]>> Proceed.

[00:21:49]>> And Layla, O'Connell.

[00:21:51]>> Sir.

[00:21:53]>> Perhaps if we demonstrated [music] >> Sir.

[00:21:57]>> Layla is playing the U-boat captain, and O'Connell is playing the escort commander.

[00:22:02]Layla comes in from the rear on the surface, fires off her torpedo, dives deep, and waits for [music] the convoy to pass over.

[00:22:12]>> Ship torpedoed.

[00:22:14]Fifth column, third ship.

[00:22:16]Time in, 10:04.

[00:22:19]Next move in 2 minutes.

[00:22:21]>> O'Connell does the standard Buttercup tactic. She instructs her escorts to scatter outside of the convoy.

[00:22:30]>> But the U-boats aren't escaping in that direction. The U-boats are sitting quietly within the convoy.

[00:22:38]>> U-boat undetected. U-boat escaped.

[00:22:43]Sir, the reason I asked you here so urgently, O'Connell, would you now enact the what you counter tactic?

[00:22:53]Play again.

[00:23:00]Ship torpedoed.

[00:23:02]>> What Ogle does is, unlike Buttercup, sends her escorts to the rear, where she expects the U-boats to be trying to escape. [music] And it's there that she conducts her A-stick sonar sweeps.

[00:23:19]>> A-stick ping on 90.

[00:23:21]Likely U-boat contact.

[00:23:23]Next move [music] in 2 minutes.

[00:23:26]>> Depth charges are fired, and Laidlaw has no time to get her U-boat out of the way.

[00:23:32]>> Depth charges dropped.

[00:23:34]U-boat destroyed.

[00:23:37]Game over.

[00:23:49]Who devised this tactic?

[00:23:53]Wren Jean Laidlaw did all the boring analysis. [music] It was a question of maths, measurements, which an accountant could easily make.

[00:24:03]And Laidlaw is a qualified [music] accountant.

[00:24:13]>> Well done, Laidlaw.

[00:24:15]>> Thank you, sir.

[00:24:18]>> And do you have a name for it?

[00:24:21]>> Raspberry, sir.

[00:24:22]>> Raspberry?

[00:24:26]>> As in blowing a raspberry at Hitler, sir.

[00:24:30]>> It dawns immediately on Noble that Buttercup doesn't work.

[00:24:36]He sees that their countermeasure, Raspberry, is far superior.

[00:24:41]>> So, Percy Noble all of a sudden realizes that these war games might actually become a crucial element in the fight against donuts.

[00:24:50]>> Take down this message.

[00:24:52]The first indications have shown a cardinal error in anti-U-boat tactics.

[00:24:58]There will be a new, immediate, and concerted counterattack signaled to the fleet within the next 24 hours.

[00:25:07]Send that to the Prime Minister.

[00:25:11]And so, on your fourth stripe, Roberts, you're promoted to captain.

[00:25:17]>> Sir.

[00:25:22]>> Raspberry.

[00:25:27]>> Once a tactic has been developed, the task now is to train as many officers in that tactic as possible.

[00:25:36]>> To be used [music] when a U-boat attacks by night, star shells are fired, so the U-boat dives to avoid detection.

[00:25:45]Convoy to continue moving.

[00:25:48]Flanking escorts to conduct triangular [music] astic sweeps, like so.

[00:25:54]Stern escorts to [music] conduct zigzag sweeps.

[00:25:59]Like a fishing net, the U-boat will be caught up.

[00:26:03]Code word, Operation Raspberry.

[00:26:07]>> Operation Raspberry.

[00:26:10]>> Yes, sir.

[00:26:12]Operation Raspberry.

[00:26:15]Do you think you've got the hang of it?

[00:26:17]Yes?

[00:26:19]Good.

[00:26:20]You're first up.

[00:26:23]>> The course is about a week. They will be lectures during the morning. They'll be briefed on the tactic, and then in the afternoon, they will then have a training war game.

[00:26:37]>> Merchant ship torpedoed, fourth column, second ship.

[00:26:52]Astic sweep conducted. No ping.

[00:26:56]U-boat escaped.

[00:26:58]Play again.

[00:26:59]>> The naval commanders found themselves not doing as well as they would have hoped.

[00:27:16]>> Asdic ping on 102, likely U-boat contact.

[00:27:21]>> Often they were getting beaten once, twice, three times despite extensive experience in exactly [music] these sort of scenarios.

[00:27:32]>> Depth charges fired, no contact. U-boat escaped. Play again.

[00:27:38]>> But eventually, as they started to see how the new [music] tactics could be effective, they were finally getting the hang of Raspberry.

[00:27:54]>> Depth charges fired. U-boat depth charged. U-boat destroyed.

[00:28:00]>> This is a really promising sign for the Royal Navy.

[00:28:03]>> Well done, sir.

[00:28:05]Play again.

[00:28:09]>> But the real test of Raspberry is going to be when it's employed in actual combat.

[00:28:17]>> Convoy SC 104 runs the Atlantic Gauntlet.

[00:28:22]48 merchant vessels and six escort ships sailing from New York to Liverpool.

[00:28:33]>> The man in charge of the escort is Commander Ralph Heathcote on the destroyer HMS Fame.

[00:28:40]It's abysmal weather, massive waves, and above that, northern lights.

[00:28:48]The merchant vessels are clearly visible due to the northern lights. And the escorts had spotted a U-boat before, but lost contact.

[00:29:01]>> Have we regained contact with that U-boat to stern?

[00:29:06]>> No, sir.

[00:29:07]No smells on our asdic or radar.

[00:29:10]>> Maybe they've pulled back.

[00:29:12]This sea is bloody rotten.

[00:29:14]But the aurora borealis is lighting us up for all to see.

[00:29:18]We'll be easy to spot.

[00:29:21]>> So will they.

[00:29:23]Mhm.

[00:29:24]Stay vigilant.

[00:29:27]Continue scanning with asdic.

[00:29:34]>> Raspberry.

[00:29:36]>> Sir?

[00:29:38]>> Raspberry. Raspberry. Raspberry.

[00:29:41]>> Raspberry. Raspberry.

[00:29:45]>> Dive. North.

[00:29:47]>> Up.

[00:29:55]>> Any smells on asdic?

[00:29:57]>> No, sir. No pings.

[00:30:00]>> We must have missed them.

[00:30:01]Bastards.

[00:30:03]Return to the convoy screen.

[00:30:05]>> Aye, sir.

[00:30:06]>> Heavy weather makes the task of detecting and hunting U-boats even harder. It's very, very difficult under these conditions to keep a constant contact even if you're lucky enough to detect a U-boat.

[00:30:22]>> The convoy plows ahead.

[00:30:25]>> It must have been rather nerve-racking for the crews of the surface vessels because the U-boats had already torpedoed three merchant ships.

[00:30:34]Maybe even more U-boats were gathering.

[00:30:38]That next night, their worst nightmare came true.

[00:30:41]>> Fire!

[00:30:42]>> Fire!

[00:30:50]>> 10 seconds.

[00:30:56]>> 20 seconds.

[00:31:14]>> Hit.

[00:31:23]>> Raspberry.

[00:31:25]>> Raspberry, raspberry, raspberry.

[00:31:28]>> The escorts turned to the rear and they start to use the asdic sonar to sweep for the U-boat.

[00:31:38]>> If the U-boat was picked up by the asdic, the crew could actually hear it.

[00:31:42]But it was not a ping like they showed in the movies, it sounded more like a handful of gravel thrown against the hull of the U-boat like a whoosh.

[00:31:54]>> Asdic.

[00:31:59]>> There's nothing you can do.

[00:32:01]You're waiting.

[00:32:03]You're counting the pings. When the pings go quiet, you don't know whether that means that the escort has given up or that the depth charges are going to follow.

[00:32:16]>> Sir, asdic ping, U-boat detected.

[00:32:18]>> Excellent work, gentlemen.

[00:32:21]Full speed ahead.

[00:32:22]Fire five depth charge pattern on my order.

[00:32:27]>> [music] >> Fire.

[00:32:31]>> Fire.

[00:32:32]>> [music] >> Damage report.

[00:33:10]>> The U-boat is heavily damaged, and this forces the captain to retreat back to the home base for repairs.

[00:33:20]So, in this case, the U-boat is not sunk, but forced out of action.

[00:33:28]>> Sir, debris detected. U-BOAT HIT.

[00:33:33]>> WE GOT HIM.

[00:33:34]>> Every U-boat that's driven away from a convoy is a victory. You don't need to destroy a U-boat. They need to get the trade through. That's the objective of the whole operation.

[00:33:44]>> In the Battle of SC 104, the escorts damage another U-boat and sink two more.

[00:33:52]It marks an incredible turning point.

[00:33:55]Raspberry works.

[00:33:58]That U-boat headquarters Dönitz tallies the losses.

[00:34:02]>> Herr Admiral, eight merchant ships sunk, but two U-boats destroyed, two damaged.

[00:34:16]The escorts are doing something differently. They're more effective.

[00:34:26]Perhaps a change in sonar.

[00:34:28]Perhaps, Herr Admiral.

[00:34:31]>> Dönitz realizes something is going on, but he doesn't know about W.A.T.U. and the new tactics. He can't imagine that he is being outplayed at his own game.

[00:34:49]>> Soon more U-boats are sunk using the Raspberry tactic.

[00:34:54]The Royal Navy threw their weight behind [music] the tactical unit.

[00:34:58]More and more Wrens are assigned to Roberts' staff.

[00:35:03]>> Is this seat taken?

[00:35:04]>> No, please sit.

[00:35:06]>> Thanks.

[00:35:10]I'm June Duncan.

[00:35:12]>> Jean O'Neill, pleased to meet you.

[00:35:14]You're from Liverpool, too?

[00:35:16]>> Lived there all my life. You?

[00:35:18]>> Me, too, except for a couple years on the Isle of Man.

[00:35:21]How long have you been a Wren?

[00:35:23]>> Not long. This is my first job.

[00:35:25]>> Mine, too.

[00:35:27]I was rejected by the Wrens twice, both times for being underweight.

[00:35:31]>> And did you pass the physical?

[00:35:32]>> On the third try, my mother had the bright idea to sew silver ingots into the hem of my coat.

[00:35:39]Tipped [snorts] the scales in my favor.

[00:35:42]>> June Duncan is one of the new recruits [music] that Roberts gets into his department.

[00:35:48]>> This is Nancy.

[00:35:49]>> Daisy.

[00:35:50]>> He ends up with 66 Wrens [music] under his command.

[00:35:55]>> And Roberts will need all the staff he can get.

[00:35:59]Now the Royal Navy encourages all officers to [music] take the W.A.T.U.

[00:36:03]course.

[00:36:04]>> 5,000 officers go through the Western Approaches Tactical Unit, or W.A.T.U.

[00:36:08]for short.

[00:36:10]>> W.A.T.U. want the captains in charge of the escort ships to have these tactics at the tip of their fingers, so that if a convoy ship is hit, they know exactly what to do and they get rid of that U-boat threat.

[00:36:23]>> Gentlemen, welcome to the Western Approaches Tactical School.

[00:36:29]Make your mistakes here and you won't make them at sea.

[00:36:33]>> During WATO's existence, it develops a number [music] of tactics to cover a host of situations.

[00:36:39]>> Operation Artichoke.

[00:36:42]To be used when a U-boat attacks by day or by strong moonlight.

[00:36:47]The escort astern the convoy immediately proceeds to the torpedoed [music] ship scanning with ASDIC.

[00:36:54]All other escorts turn and speed astern the convoy until 6,000 yd past the stricken ship.

[00:37:02]Here, they turn back and ASDIC sweep behind the convoy scanning for U-boats.

[00:37:09]So, who thinks they can sink a U-boat?

[00:37:15]>> Merchant ship [music] torpedoed. Seventh column, second ship.

[00:37:19]Next move in 2 minutes.

[00:37:22]>> Operation Observant, also known as the square search. To be conducted when a U-boat has been detected by ASDIC, but lost.

[00:37:30]The escort ships conduct a 2-mi sweep in a square shape around the last known U-boat location.

[00:37:37]If the U-boat tries to escape the square, ASDIC will detect it >> [music] >> and the U-boat can be depth charged.

[00:37:44]>> Operation Half Raspberry.

[00:37:47]Similar [music] to Raspberry, however, some escorts are held back at the group commander's discretion [music] to protect the convoy whilst the other escorts hunt for U-boats.

[00:38:00]>> Peter Gretton will go down in history as one of the great hunters of the sea in terms of his capacity to down U-boats.

[00:38:08]He is one of those 5,000 officer commanders who is encouraged to rethink his game >> [music] >> in WATO.

[00:38:16]Gretton does say that learning these tactics make officers who aren't necessarily all together very clever think for the first time in their careers.

[00:38:28]>> No, sir.

[00:38:29]I don't think you should do that.

[00:38:31]>> Operation Pineapple.

[00:38:33]Used when a U-boat is detected ahead of the convoy.

[00:38:36]Escorts at the front and the flanks speed towards the U-boat firing star shells for 15 minutes.

[00:38:44]The aim is to force the U-boat to dive, trick it into encirclement so it can be detected and sunk.

[00:38:52]Depth charges dropped, U-boats destroyed.

[00:38:56]>> At the end of each game, Raum and the Wachtel team would get all of the men together and assess exactly [music] how the game went.

[00:39:05]>> What they're teaching is vital if Britain wants to win the Battle of the Atlantic.

[00:39:11]>> It is the [music] war of the little ships and the lonely aircraft, long, patient, and unpublicized against our two great enemies, the U-boat and the cruel sea.

[00:39:25]Your survival and the survival of Britain depends on what you've learned here.

[00:39:37]>> For the USA, their merchant shipping losses have finally become too great.

[00:39:44]>> The German Navy has complete license off the US East Coast in 1942. The Americans have determined that they're simply not going to run system of convoys, and that creates a safe environment for the U-boats to operate.

[00:39:56]The Germans have this enormous second happy time where Allied losses are high and U-boat losses are virtually negligible.

[00:40:04]>> But early plans are made to send American troops to North Africa to help the British drive the German and Italian armies out.

[00:40:14]US President Franklin D. Roosevelt now sets his sights on the Nazis in Europe.

[00:40:22]>> The problem with that, of course, it meant transporting a million and a half men across the Atlantic and all their supplies and all their equipment.

[00:40:31]None of this can happen. No invasion of Europe can take place unless the allies win the Battle of the Atlantic. It's that simple. They have to suppress the U-boat threat.

[00:40:40]>> The USA begins a massive construction program to build more escort destroyers.

[00:40:47]With these, they finally adopt the British convoy system, sailing merchant vessels together so they can be better protected.

[00:40:57]The result for Dönitz is costly.

[00:41:01]The U-boat tonnage tally off the US coast plummets.

[00:41:05]>> The improved American defensive measures spells the end of the second happy time.

[00:41:10]>> But Dönitz has a new plan to make his wolf packs even deadlier.

[00:41:16]>> U-boats operating off the coast are at risk of being spotted from the air.

[00:41:22]When they are, their position is promptly relayed to the convoys, taking away our greatest weapon, the element of surprise.

[00:41:32]The U-boat is also forced to dive [music] or risk being bombed, slowing down its progress, making it harder for wolf packs to assemble. Some are missing convoys altogether.

[00:41:46]But, I have identified a weakness.

[00:41:53]Allied aircraft are land-based, meaning they can only fly so far out to sea before they have to return or risk running out of fuel.

[00:42:11]Which means there is a black hole in the middle of the Atlantic where their aircraft can't protect them.

[00:42:23]>> Dönitz realizes that the allies weak point is now the mid-ocean, the air gap.

[00:42:29]>> In 1942, the middle of the Atlantic became the main battlefield for the U-boats.

[00:42:37]>> We will quickly show Britain and America that the Atlantic trade route is shut.

[00:42:46]>> Despite the early success of the Western Approaches Tactical Unit, Churchill is still furious that the allies haven't turned the tide in the Battle of the Atlantic.

[00:42:58]In November 1942, there is a shake-up at the top of Western Approaches Command.

[00:43:04]The center of operations for North Atlantic convoys >> Percy Noble is pushed sideways. He goes to the British Admiralty delegation in Washington.

[00:43:15]What they need by November of 1942 is a bit of a bastard.

[00:43:21]And that's what they get with Max Horton.

[00:43:24]>> So, Max Horton is a submariner from the First World War. Of course, the enemy's beneath the waves a lot of the time.

[00:43:33]He's been tapped on the shoulder by Churchill, but still ain't good enough.

[00:43:36]We still haven't won the Battle of the Atlantic.

[00:43:40]>> Admiral Max Horton wants to know what all of his staff are doing. He wants to make sure that everyone is making their contribution to victory.

[00:43:47]Which means one of the things he wants to understand is how WATO is operating.

[00:43:51]If it isn't contributing, then he will end it.

[00:43:55]>> Once more, they have a fight on their hands to prove themselves.

[00:44:00]>> The Western Approaches Tactical Unit.

[00:44:04]>> Sir, A Roberts, we spoke on the phone.

[00:44:08]>> Did we?

[00:44:09]I don't recall.

[00:44:12]And what duty do you perform on my staff?

[00:44:15]>> Director, sir, of the tactical school.

[00:44:18]>> Oh, I see.

[00:44:22]Ah, yes, the infamous board where you uh play your games.

[00:44:28]>> Yes, sir.

[00:44:30]>> Not interrupting one, am I?

[00:44:32]>> Not at all, sir.

[00:44:34]I'm glad you could find the time to come and see us.

[00:44:37]>> What exactly are you doing?

[00:44:39]>> We're wargaming a new tactic, sir.

[00:44:42]Peter search.

[00:44:44]Designed to destroy a U-boat detected on the flanks of the convoy.

[00:44:52]>> Is it effective?

[00:44:54]In your game.

[00:44:58]>> Would you like to play, sir?

[00:45:00]>> [music] >> As a U-boat captain.

[00:45:04]I must warn you, Roberts.

[00:45:05]>> I have some experience fighting in subs from the first war.

[00:45:08]>> Then you should be fine, sir.

[00:45:10]After all, you don't need to sink a ship.

[00:45:12]All you need to do is survive.

[00:45:15]Should be straightforward, sir.

[00:45:17]Someone of your experience.

[00:45:24]>> Very well.

[00:45:25]Let the game commence.

[00:45:30]>> Sir.

[00:45:31]Behind here, sir.

[00:45:36]>> Max Horton plays from behind a screen opposite where the person playing the British convoy is.

[00:45:44]They can't see each other.

[00:45:46]>> The U-boat player in tactical development wargame has to have the same limited information that an escort commander gets. You want the U-boat to react as if it's for real. It has to be behind the screen because if he picks up any additional movements or detail. He will know too much. It's vital if you want the U-boat commander to act like a real U-boat commander.

[00:46:13]>> Asdic ping. U-boat detected. Time in 09:34.

[00:46:18]Next move in 2 [music] minutes.

[00:46:30]Depth charges dropped.

[00:46:32]U-boat destroyed.

[00:46:35]Game over. What?

[00:46:38]Play again.

[00:46:40]>> Okay, pot luck. Could happen. And he sets it up again.

[00:46:44]>> Very well.

[00:46:56]Depth charges dropped. U-boat destroyed.

[00:47:00]Game over.

[00:47:01]>> His U-boat is spotted and sunk.

[00:47:03]>> Play again.

[00:47:04]>> The third game, he also loses.

[00:47:06]>> Play again.

[00:47:07]>> The fourth game, he also loses.

[00:47:10]>> Depth charges dropped. U-boat destroyed.

[00:47:14]>> He's dead.

[00:47:15]And he's dead.

[00:47:16]>> U-boat depth charged.

[00:47:18]U-boat destroyed.

[00:47:20]Game over.

[00:47:23]>> Enough is enough.

[00:47:26]>> All right, Roberts. You made your point.

[00:47:28]I admit defeat.

[00:47:30]Now show me the officer who bested me.

[00:47:36]>> O'Connell.

[00:47:39]Sub Lieutenant Janet O'Connell.

[00:47:42]The woman who beat you 5-0.

[00:47:45]>> What?

[00:47:48]You rigged it.

[00:47:49]>> No, sir. O'Connell was merely following a new tactic devised after months of analysis by our own Jean Egret.

[00:48:00]>> You.

[00:48:01]>> So, by wargaming every scenario, we anticipated your moves, deduced your course, so knew exactly where to find you and destroy you.

[00:48:15]>> Well, let's hope it works at sea.

[00:48:18]Because now Dönitz has his 300 U-boats.

[00:48:21]He'll be hell-bent on using them to turn the Atlantic into a convoy graveyard.

[00:48:32]>> ONS 5.

[00:48:34]It's one of the largest single convoys ever undertaken.

[00:48:39]>> I want this convoy destroyed.

[00:48:42]>> Message to U-boat headquarters, convoy spotted, speed 8 to 10 knots, bearing 2070.

[00:48:48]>> We have designed these tactics which will save you time when you're at sea.

[00:48:52]>> U-boat sighted at a range of about 2 miles.

[00:48:56]>> Seconds that can save lives.

[00:48:58]>> Observant.

[00:49:00]Observant.

[00:49:01]>> Do you ever lose faith in what we're doing here?

[00:49:05]>> We will have to live with our decisions, Roberts.

[00:49:08]>> What if we don't prevail out there?

[00:49:11]>> If there's going to be an unconditional surrender, it will be theirs, not ours.