When the Cuban Navy Sank the German Submarine U-176 in World War II

On 15 May 1943, the Cuban Navy sank the German submarine U-176 off northern Cuba. The patrol vessel CS-13 dropped depth charges after a U.S. Navy Kingfisher marked the U-boat's position. The loss of all 53 crew members aboard was recorded at position 23.21N, 80.18W.

The engagement on 15 May 1943

The engagement that destroyed U-176 took place on 15 May 1943 in the Florida Straits north-east of Havana. By then, the submarine had completed three war patrols and sunk 11 merchant ships totaling 53,307 gross register tons. That record made it a proven threat to Allied shipping in the Caribbean. The Cuban Navy was patrolling those waters alongside U.S. forces, watching for enemy submarines.

U-176 was not a newcomer to the area. The boat had operated in the Steinbrinck and Lohs wolfpacks in August 1942. On 25 August 1942, after a successful attack on convoy ONS 122, U-176 sighted the British destroyer HMS Viscount and fired a stern torpedo that missed. The destroyer then dropped five depth charges, none of which caused damage. Later that morning, Viscount found the boat again in thick fog, opened fire with 20mm guns, and forced a steep crash dive to about 120 meters. Five more depth charges caused only minor damage. uboat.net cites Admiralty reports and U-176's war diary for these attack records. Despite those attacks, the boat had not lost any crew members before its final patrol.

In December 1942, a Catalina flying boat attacked U-176 off Recife, Brazil, dropping bombs as the boat dived. The submarine was forced back to the surface and strafed before it could dive again. Battery damage limited its ability to submerge, and repairs took two days.

On 15 May 1943, a U.S. Navy Vought OS2U-3 Kingfisher from squadron VS-62 USN/1 spotted the U-boat as it began a crash dive. A crash dive is an emergency maneuver used to get below the surface quickly. The commander aboard was Korvettenkapitän Reiner Dierksen, who had led U-176 since commissioning. The aircraft dipped its wings and dropped smoke floats to mark the position. The Cuban patrol craft CS-13 then approached the marked spot.

CS-13 released a pattern of three depth charges. Four explosions followed on the submerged U-boat. U-176 was destroyed at position 23.21N, 80.18W, north-east of Havana. All 53 crew members aboard died. uboat.net records the boat as sunk by depth charges from the Cuban patrol craft CS 13, with no survivors recovered.

Why U-boats hunted in Cuban waters

German submarines hunted in Cuban waters because the Florida Straits and nearby Caribbean routes carried merchant traffic that was essential to the Allied war effort. Tankers, freighters, and bauxite carriers moved through these waters between Gulf ports, the Caribbean islands, and the Atlantic. The Florida Straits, the channel between Florida and Cuba, funneled much of this traffic into a predictable route that submarines could patrol. Cuba declared war on the Axis in December 1941, and its northern coast sat directly on that shipping lane.

From early 1942, U-boats shifted patrols to the western Atlantic and Caribbean. A wolfpack was a group of submarines that coordinated attacks on convoys. U-176 sailed with the Steinbrinck and Lohs groups in August 1942. The Naval History and Heritage Command is the U.S. Navy's historical office and catalogs World War II operational records used to study anti-submarine campaigns. U-176 went on to sink 11 ships totaling 53,307 gross register tons, which made it part of the campaign's toll on merchant shipping.

For Cuba in World War II, submarines were not a distant threat. The losses inflicted by U-176 illustrate what merchant crews faced along the route that connected the Gulf of Mexico to the wider Atlantic. Germany's aim was to cut the flow of oil and war materials from the Caribbean, and each ship sunk reduced Allied capacity. The loss of U-176 off northern Cuba removed one submarine from that route.

U-176 at a glance

The following table summarizes U-176's technical and career data from uboat.net’s U-176 page.

The boat's track record of 11 ships sunk in three patrols explains why Allied air and naval forces tracked it closely in May 1943. Its move from training to the 10th Flotilla in August 1942 placed it on active Atlantic and Caribbean patrols.

CS-13 and the Cuban Navy

CS-13 was the Cuban Navy vessel that carried out the attack on U-176. A patrol craft, sometimes called a submarine chaser, is a small warship designed for coastal escort and anti-submarine work. The Cuban Navy used such craft to guard the approaches to its northern ports and to work with U.S. forces after Cuba entered the war in December 1941.

The loss record for U-176 identifies the attacking vessel as Cuban patrol craft CS 13. The craft dropped a pattern of three depth charges on the submerged U-boat after a U.S. Navy Kingfisher marked the position with smoke floats. Four explosions followed, and the submarine was destroyed.

Depth charges were cylindrical explosive weapons dropped or launched from a ship and set to detonate at a predetermined depth. A pattern of three charges increased the chance that at least one would explode close enough to cripple a submerged submarine. Smoke floats released by the Kingfisher marked the spot where U-176 had dived, which allowed CS-13 to attack a target it could no longer see.

The action brought together U.S. air spotting and Cuban naval attack. After Cuba entered the war in December 1941, its navy concentrated on coastal defense and convoy escort. Patrol craft like CS-13 were suited to shallow-water work and could respond quickly to sightings reported by aircraft or lookouts. This made them useful partners for the larger U.S. Navy forces operating in the Caribbean.

Aftermath and how the battle is remembered

The sinking of U-176 removed an active submarine from the Florida Straits and prevented further attacks on merchant shipping along that route. The boat went down at position 23.21N, 80.18W with all 53 crew, including commander Reiner Dierksen, and no survivors were recovered.

The action is documented in U-boat loss records and U.S. Navy historical holdings. It is remembered as a clear instance of the Cuban Navy engaging and destroying an enemy submarine during World War II. Cuban and U.S. forces together ran patrols across the Caribbean, and CS-13's role formed part of that broader campaign.

Historians and researchers can verify the engagement through uboat.net and the Naval History and Heritage Command, which hold the underlying loss data and operational records. For more on how CubaNow approaches historical coverage, see CubaNow’s editorial approach.

After the war, the loss position remained recorded as 23.21N, 80.18W in U-boat loss records. The 11 ships U-176 had sunk before its loss make the engagement a meaningful defensive success.

Sources and where the records live

uboat.net's U-176 page provided the technical data, loss position, patrol history, and casualty figures used in this article. The Naval History and Heritage Command is the U.S. Navy's central historical office; researchers can consult its catalog for World War II operational records that document the patrol environment. Together with standard reference works on U-boat losses, these records allow the engagement to be verified against primary documentation.

FAQ

Did Cuba fight in World War II? Yes: Cuba declared war on the Axis in December 1941, and its navy and merchant crews faced U-boat attacks in the Caribbean.

How did Cuba sink U-176? The patrol vessel CS-13 located and attacked U-176 with depth charges off northern Cuba on 15 May 1943, after a U.S. Navy Kingfisher marked the submarine's position.

What type of submarine was U-176? It was a German Type IXC ocean-going U-boat built for long-range patrols.

Did anyone survive the U-176 sinking? No: all 53 crew aboard were lost, according to uboat.net.