Convoy OB 318 facts for kids

Quick facts for kids Convoy OB 318
Part of Battle of the Atlantic
U-110 and HMS Bulldog
Date 7–10 May 1941 Location Atlantic Ocean, South of Iceland Result British victory
Belligerents
United Kingdom	Germany
Commanders and leaders
Convoy Commodore: WB MacKenzie RNR Escort: Cdr AJB Baker-Cresswell Boarding Party: Sub-Lt. David Balme	Admiral Karl Dönitz
Strength
40 freighters 3 Destroyers 3 Corvettes 2 Naval trawlers	4 submarines
Casualties and losses
7 freighters sunk (35,315 GRT) 40 killed/drowned 2 freighters damaged	1 submarine captured 14 killed/drowned 32 captured 2 submarines damaged

Convoy OB 318 was a group of ships traveling together across the North Atlantic during World War II. This event was part of the larger Battle of the Atlantic, where Allied convoys were attacked by German U-boats (submarines). A very important part of this convoy's story was "Operation Primrose." During this operation, British warships like HMS Bulldog, Broadway, and Aubrietia managed to capture a German submarine, U-110. This was a huge deal because they found a working Enigma machine and secret codebooks inside the U-boat. This discovery helped the Allied forces to break Germany's secret naval codes, which changed the course of the war at sea.

The Start of the Battle

By spring 1941, German U-boats were losing more battles. So, German Admiral Karl Dönitz changed his plan. He sent his U-boat groups, called "wolf packs," further west into the Atlantic. His goal was to attack convoys before their escorts could protect them.

Convoy OB 318 was heading west from Liverpool, England, to ports in North America. It left on May 2, 1941, with 38 cargo ships. These ships were either empty or carrying important trade goods. The convoy was led by Commodore R.Adm. WB MacKenzie. It had an escort group of ten warships, later joined by eight more. Facing them were several German U-boats, including U-110, commanded by Fritz-Julius Lemp.

The Action Begins

On May 7, 1941, the U-boat U-94 spotted Convoy OB 318. It reported the convoy's location to U-boat Command. Other U-boats nearby were ordered to move in for an attack.

During May 7, five ships from Iceland joined the convoy. Also, destroyers from the 3rd Escort Group arrived. They were there to take over protection duties. Three ships and some destroyers left for Iceland, but the convoy still had ten warships protecting it.

U-94 Attacks

On the night of May 7, U-94 attacked the convoy. Its commander, Herbert Kuppisch, snuck into the convoy by diving deep. He let the lead escort ships pass over him. Then, he fired at close range, sinking two ships: Ixion and Eastern Star.

However, the British warship Rochester found U-94. Bulldog and Amazon joined the attack. They chased and attacked U-94 for four hours. U-94 was damaged and had to leave the area. But it was able to fix itself later and continue its mission.

On May 8, more escort ships joined the convoy. These included three corvettes and two trawlers. The remaining ships of the original escort group then left.

The Capture of U-110

On the evening of May 8, U-110 and U-201 found the convoy. They tracked it until morning. The two U-boat commanders decided to work together. Lemp, on U-110, would attack from the front while submerged. Adalbert Schnee, on U-201, would attack from the back. They thought the escort ships would have left by then.

On the morning of May 9, U-110 moved into position and began its attack. Lemp was surprised to find the escort ships still there. But he managed to get inside the convoy and sink two ships. As Lemp was aiming for a tanker, Aubrietia spotted his periscope. It then found U-110 using ASDIC (a type of sonar).

Aubrietia quickly warned other ships and dropped depth charges. U-110 dove deep but survived the first attack. Soon, the destroyers Bulldog and Broadway joined Aubrietia. Their combined attack was so strong that Lemp was forced to bring U-110 to the surface.

As the U-boat surfaced, some German sailors tried to man their guns. But the British ships fired at them. Lemp saw that Bulldog was getting ready to ram his submarine. So, he quickly ordered his crew to abandon ship. Commander Joe Baker-Cresswell, leading Bulldog, decided not to ram. Instead, he wanted to try and capture the U-boat.

The German survivors jumped into the water, including Lemp. It seems Lemp realized Bulldog wasn't going to ram. He tried to go back inside U-110 to destroy the secret equipment and codebooks. But he failed and died in the attempt. U-110 was badly damaged and sinking, but it was still afloat.

Bulldog pulled alongside U-110. Sub-Lieutenant David Balme led a small team onto the U-boat. They quickly started searching for anything valuable. Balme's team found codebooks, maps, and, most importantly, a complete and working Enigma machine. The British crew didn't fully understand how important their discovery was at the time.

Before they could move all the equipment, Bulldog had to leave. It had received a message about another submarine nearby. Balme and his men were left on U-110 for over an hour. Then, Bulldog returned to pick them up.

U-201 and U-556 Attacks

Meanwhile, Schnee, on U-201, also attacked. He sank one ship and damaged another. He was then attacked by Amazon, Nigella, and St Apollo. U-201 was damaged and had to retreat.

In the early hours of May 10, U-556 found Convoy OB 318. It attacked right away, damaging one ship. The convoy was at its dispersal point, meaning the ships were about to split up and head to their different destinations. The escort ships left to meet their next assignment. However, U-556 managed to stay with a group of ships heading south-west. During the day, it sank two more.

What Happened Next and Why It Mattered

U-boats sank five ships from Convoy OB 318 during the main battle. Three more ships, including the convoy leader's ship Colonial, were sunk by U-boats patrolling near their destinations. Still, 33 ships safely reached their destinations over the next two weeks.

Commander Baker-Cresswell tried to tow U-110, but it sank within hours because of the damage it had taken. Lemp and 14 of his crew were lost. However, 4 officers and 28 men were rescued and taken as prisoners of war to Scapa Flow. Experts from Bletchley Park, a top-secret British code-breaking center, were waiting there. They were amazed by what they collected from U-110 and took it back to their base.

The capture of the Enigma machine was kept a huge secret. None of the crew members knew how important it was. This machine greatly helped the code-breakers at Bletchley Park. They were trying to break Germany's secret naval codes. This was the first fully working Enigma machine they captured. It helped them to break the naval codes, along with other codes captured from German weather ships that same year.

Thanks to this Enigma machine, Bletchley Park could tell the Royal Navy where most U-boat groups were. This allowed the Navy to steer convoys away from danger. The difference was huge. In June 1941, Allied shipping losses were around 432,000 tons. But by August, they had dropped to less than 80,000 tons.

One of the most important finds was the Reservehandverfahren cipher. Bletchley Park first solved this code in June 1941 using documents from U-110. Later, more important codebooks were captured from U-559 in October 1942. After that, Alan Turing and his team used cryptanalysis (code-breaking) to solve it for over three years. During that time, they read about 1,400 secret messages.

Commander Baker-Cresswell received the DSO medal and was promoted to captain. King George VI told him that capturing the U-110 code material was "the most important single event in the whole war at sea."

Allied Merchant Ships Sunk or Damaged

Name	Flag	Tonnage (GRT)	Notes
Ixion (1912)	United Kingdom	10,263	Sunk on 7 May by U-94
Eastern Star (1920)	Norway	5,658	Sunk on 7 May by U-94
Bengore Head (1922)	United Kingdom	2,609	Sunk on 9 May by U-110
Esmond (1930)	United Kingdom	4,976	Sunk on 9 May by U-110
Gregalia (1929)	United Kingdom	5,802	Sunk on 9 May by U-201
Empire Cloud (1941)	United Kingdom	5,969	Damaged on 9 May by U-201. Repaired later.
Aelybryn (1938)	United Kingdom	4,986	Damaged on 10 May by U-556 after convoy dispersed.
Empire Caribou (1919)	United Kingdom	4,861	Sunk on 10 May by U-556 after convoy dispersed.
Gand (1919)	Belgium	5,086	Sunk on 10 May by U-556 after convoy dispersed.
Berhala (1927)	Netherlands	6,622	Sunk by U-38 after convoy dispersed.
Colonial (1926)	United Kingdom	5,108	Sunk by U-107. Carried the convoy commodore.

Convoy Escorts Involved in the Action

U-boats Hit

The Film U-571

The movie U-571 was partly inspired by the capture of U-110. However, the film changed the story to make it seem like American sailors captured the Enigma machine. This made many people in Britain upset and angry.

The anger was so strong that in the British Parliament, Prime Minister Tony Blair agreed that the film was "an affront" to British sailors. This means it was an insult to their bravery and actions.

In response to a letter from Paul Truswell, a Member of Parliament, U.S. President Bill Clinton wrote back. He explained that the film's plot was just a made-up story. Despite the criticism, David Balme, who led the real boarding party, was interviewed by the film's director, Jonathan Mostow. The capture of U-110 was even mentioned at the start of the film's end credits, as a way to acknowledge the true story.

See also

• Ultra
• Cryptanalysis of the Enigma
• Kurzsignale