The only underwater submarine confrontation in history

The British submarine HMS Venturer and German U-864 faced off in 1945, creating the only underwater battle between two submarines in history.

The submarine HMS Venturer before setting sail. Photo: Wikipedia

During the two world wars, there were dozens of fierce battles between diesel-electric submarines, but most of the ships were destroyed when they surfaced due to battery failure.out of powerHowever, the battle between the British submarine HMS Venturer and the German U-864 in 1945 was the only engagement in history when both opponents were submerged, according toNational Interest.

To help the Japanese fascists maintain their fighting power and divide the Allies, on February 5, 1945, Germany deployed the submarine U-864 carrying the Jumo 004 jet engine design and two Messerchmitt factory engineers to Japan to help the country develop domestic jet fighters. On board the submarine were also documents on the development of the V-2 ballistic missile and two Japanese technical experts.

In addition, the U-864 submarine also carried more than 67 tons of liquid mercury contained in 1,857 steel cylinders to serve the manufacture of detonators. Captain Ralf-Reimar Wolfram's mission was to move the U-864 north, around Norway and through the Arctic region of the Soviet Union to hand over these documents and supplies to Japan.

The U-864 was a Type IXD2 class cruiser submarine, larger than the standard Type VII. It was designed for long transoceanic patrols and had large cargo holds. Before setting out, the U-864 was fitted with a snorkel, a feature never seen before on a submarine of its time, allowing it to take in air without surfacing.

However, the German submarine ran into trouble shortly after departure. After leaving Kiel on December 5, 1944, the ship ran aground and was forced to undergo repairs in Bergen, Norway. In this port, U-864 suffered further damage when it was hit by a 5.5-ton bomb from a British bomber.

Unfortunately for Captain Wolfram, the British Navy had long since learned of the submarines’ communications with German command. By February 1945, the British Navy had decoded U-864’s communications and decided to spring a trap.

London decided to deploy the HMS Venturer, the first of its new V-class submarines, to hunt down and destroy U-864 off Norway. The British submarine was armed with only eight torpedoes compared to U-864’s 20, but could travel at 10 mph underwater, one and a half times faster than its opponent. Captain James S. Launders, commander of HMS Venturer, had sunk 12 Axis surface ships and destroyed the German submarine U-711 in November 1944.

SubmarineType IXD2, same type as U-864. Photo: Wikipedia

Launders decided to use short-range passive sonar instead of the long-range active sonar system ASDIC to ensure secrecy and avoid the enemy detecting the signal from ASDIC. However, the British commander did not know that U-864 had left him far behind.

The German submarine was lucky to escape detection by HMS Venturer when its diesel engine malfunctioned and caused a loud noise that threatened its ability to remain hidden. However, Captain Wolfram did not know that his decision to return to Bergen for repairs would put his submarine in danger.

On February 9, the passive sonar operator on HMS Venturer picked up an acoustic signal that was believed to be from a diesel engine on a fishing boat. Launders approached the location of the sound, then used a periscope to observe and discovered a periscope-like object in the distance. In fact, this could be the snorkel of the U-864. Launders had HMS Venturer remain submerged, secretly approaching and tailing the German submarine.

Launders had intended to wait for U-864 to surface before launching a torpedo attack. However, the snorkel allowed the German submarine to remain submerged for longer than expected. U-864 began to maneuver, possibly locating the British submarine. After three hours of pursuit, HMS Venturer’s batteries began to run low and it would soon have to surface. Commander Launders decided to attack U-864 while it was still submerged.

Estimating the depth of the German submarine based on the height of the snorkel above the water, Launders calculated the target parameters for the torpedo launch. The British commander assumed that the enemy would detect the torpedo launch, so he considered the option of firing when the enemy maneuvered to avoid it.

HMS Venturer fired all four torpedoes at 17.5-second intervals, then dived to avoid a counterattack. U-864 also dived and maneuvered to avoid the torpedoes. After four minutes, she had avoided three of the four torpedoes.

However, the fourth torpedo, fired at its deepest point, struck U-864 and broke it into three pieces. The terrible sound of metal shattering and bolts flying filled HMS Venturer’s sonar system. The German submarine sank to the bottom at a depth of 150 meters with 73 sailors on board, effectively ending the German supply operation to Japan.

The bow and stern of the U-864 on the seabed. Photo: Wikipedia

According to military expert Sebastien Roblin, diesel-electric submarines in World War II spent most of their time on the surface running diesel engines, which generated electricity to charge batteries. The energy stored in the batteries was only enough for a few hours, limiting their ability to hide at sea. Their submerged speed was only one-third of their surface speed, so submarines only submerged when ambushing or avoiding enemy ships.

Hunting enemy submarines at that time also encountered many difficulties when homing torpedoes and advanced sensor systems did not appear. Sonar systems began to become popular, but passive sonar had too short a range, while active sonar could only determine the direction and distance parameters to enemy submarines, unable to determine the depth for effective attack. Besides, active sonar also easily revealed its position and alerted enemy submarines.

Torpedoes in World War II were designed to float near the surface, allowing them to strike the keel of an enemy ship. They were difficult to adjust to attack underwater targets, especially when the commander did not have accurate parameters of the enemy. Therefore, the sinking of U-864 by HMS Venturer while both ships were submerged was an extraordinary feat.

In 2003, the Norwegian navy found the wreck of U-864 three kilometers off Fedje Island, where toxic mercury was leaking into the surrounding environment. After 15 years of assessing the risks of salvaging the ship, in February 2017, the Norwegian government decided to cover U-864 with 0.5 meters of sand and 160,000 tons of rock to prevent contamination.

According to VNE