Cuba during World War II The history of Cuba during World War II begins in 1939 . Because of Cuba ' s geographical position at the entrance of the Gulf of Mexico , Havana ' s role as the principal trading port in the West Indies , and the country ' s natural resources , Cuba was an important participant in the American Theater of World War II , and subsequently one of the greatest beneficiaries of the United States ' Lend - Lease program . Moreover , Cuba declared war on the Axis powers in December 1941 , making it one of the first Latin America n countries to enter the conflict , and by the war ' s end in 1945 its military had developed a reputation as being the most efficient and cooperative of all the Caribbean nations . History . Brú and Batista . Federico Laredo Brú was the President of Cuba when the war began in 1939 . His one significant World War II - related crisis before leaving office in 1940 was the MS " St . Louis " affair . The MS " St . Louis " was a German ocean liner carrying over 900 Jewish refugees from Germany to Cuba . Upon arriving in Havana , the Cuban government refused to allow the refugees to land because they did not have proper permits and visa s . After sailing north , the United States and Canadian governments also refused to accept the refugees , and so the " St . Louis " sailed back across the Atlantic , and dropped her passengers off in Europe . Some thenceforth went to Britain , but most went to Belgium and France , which were soon overrun by German forces . Ultimately , because of the refusal to take in the Jewish refugees , many were taken prisoner by the Germans and subsequently killed in concentration camps . Following the 1940 Cuban elections , Brú was succeeded by the " strongman and chief " of the Cuban Army , Fulgencio Batista . At first , the United States was concerned about Batista ' s intentions ; whether he would align his country with the Axis cause , or that of the Allies . Batista , shortly after becoming president , legalized a pro - fascist organization linked to Francisco Franco and his regime in Spain , but fear of any Nazi sympathies was dispelled when Batista sent the British a large quantity of sugar as a gift . Later , fear of Batista ' s possible sympathy for Franco was also dispelled when the president suggested to the United States that it launch a joint US - Latin American invasion of Spain , in order to overthrow Franco and his regime . This plan , however , did not materialize . Batista ' s support for the Allied cause was confirmed in February 1941 , when he ordered all German and Italian consular officials to leave his country . Cuba entered the war on December 8 , 1941 , by declaring war on Japan , which a day before had launched a devastating attack on the United States Navy base at Pearl Harbor , Hawaii . Cuba then declared war on Germany and Italy on December 11 , 1941 , and - following the Americans ' example - broke relations with Vichy France on November 10 , 1942 . The Battle of the Caribbean . According to Rear Admiral Samuel Eliot Morison , Cuba ' s military was the " most cooperative and helpful of all the Caribbean states " during the war , and that its navy was " small but efficient " in its fight against German U - boats . Upon Cuba ' s declaration of war on the Axis powers , Batista signed an agreement with the United States that gave the latter permission to build airfields in Cuba for the protection of the Caribbean sealanes , and he also signed a mutual defense pact with Mexico for the defense against enemy submarines in the Gulf of Mexico . Among the new American bases was the San Antonio Air Base near San Antonio de los Baños , and the San Julián Air Base in Pinar del Rio , both of which were built in 1942 and turned over to the Cuban military after the war . The United States also supplied Cuba with modern military aircraft , which were vital for coastal defense and anti - submarine operations , and refitted the Cuban Navy with modern weapons and other equipment . During World War II , the Cuban Navy escorted hundreds of Allied ships through hostile waters , sailed nearly 400 , 000 miles on convoy and patrol duty , flew over 83 , 000 hours on convoy and patrol duty , and rescued over 200 U - boat victims from the sea , all without losing a single warship or aircraft to enemy action . But even though the Cuban military was praised for its conduct , rumors persisted throughout the war that the Germans were operating small bases hidden in coves along Cuba ' s coast , which were used to resupply the U - boats . However , this fear was unjustified , and the lack of such bases in the Caribbean forced the Germans to develop supply submarines , called " milch cows , " for logistics . Cuba lost six merchant ships during the war , and the Cuban Navy was credited with sinking one German submarine . The first four sunken merchant ships were the " Manzanillo " , a steamer of 1 , 025 tons , the 1 , 685 ton " Santiago de Cuba " , the 1 , 983 ton " Mambi " , and the 5 , 441 ton " Libertad " . " Manzanillo " was sunk with the " Santiago de Cuba " on August 12 , 1942 , by U - 508 . The two ships were sailing in Special Convoy 12 when they were attacked off the Florida Keys . Altogether , thirty - three sailors were killed in what became the deadliest attack on the Cuban merchant marine during the war . Thirty others survived . The next engagement occurred on May 13 , 1943 , when the U - 176 sank the " Mambi " . The " Mambi " was with Convoy NC - 18 , sailing six miles off Manati , when a single torpedo slammed into her side , sinking her quickly . Twenty - three men were killed , including five American armed guards , who manned the ship ' s weapons . Eleven others survived , including the ship ' s master and one of the armed guards . The 2 , 249 ton American ship SS " Nickeliner " was also sunk during the same attack , after being struck by two torpedoes . The first torpedo explosion lifted the ship ' s bow out of the water and threw up a column of water and flames about 100 feet into the air . The second damaged the tanks of ammonia water the ship was carrying . Miraculously , the crew , which included seven armed guards , escaped into lifeboats without a single loss of life . They were rescued by a Cuban submarine chaser as the " Nickeliner " sank , and landed at Nuevitas . The " Libertad " was the largest Cuban merchant ship sunk in the war . On the morning of December 4 , 1943 , the 5 , 441 ton " Libertad " was sailing about seventy - five miles southwest of North Carolina ' s Cape Hatteras , with Convoy KN - 280 , when the U - 129 attacked her . Firing four torpedoes , the U - 129 struck the " Libertad " twice on the port side , causing the ship to first list severely and then sink rapidly . The crew had no time to send out distress signals , and were still lowering life rafts when the sea water reached the deck of the ship . Twenty - five men were killed , and eighteen others were rescued by the United States Navy after several hours adrift at sea . The final two Cuban merchant ships were sunk in February 1944 , apparently without the loss of life . Altogether , Cuba lost 10 , 296 tons of shipping during the war , as well as about eighty lives , including that of the American armed guards . Today there is a monument in Havana ' s Avenida del Puerto for the people who died in the attacks . The only U - boat sunk by the Cuban Navy was the U - 176 , which was the very submarine responsible for sinking the " Mambi " and the " Nickeliner " . On May 15 , 1943 , a squadron of Cuban submarine chaser s , formed by the CS - 11 , CS - 12 and CS - 13 , sailed from Isabela de Sagua toward Havana escorting the Honduran ship " Wanks " , and the Cuban ship " Camagüey " , both of which were loaded with sugar . The crews of the merchant ships , as well as those of the warships were on full alert . Just before their departure , a warning had been received that a surfacing submarine had been detected off the northern coast of Matanzas . The ships sailed in forward lines 500 yards apart . The " Camagüey " was on the flank nearest to the coast . The escort navigated at a distance of 750 - 1 , 000 yards . The CS - 12 was in front , followed by the CS - 11 with the squadron chief on board and , finally , the CS - 13 was at the rear . At 5 : 15 PM , when the convoy was off of Cayo Megano , an American Kingfisher floatplane appeared in the sky coming from the northeast . The plane went into a nosedive and , flying at low altitude , circled twice , swaying , and turning on and off its engine . According to an established code , the maneuvers were used to announce the presence of a German U - boat , and to mark it ' s exact position . The Kingfisher then dropped a smoke float . After dropping the float , the Cuban squadron chief ordered the commander of CS - 13 , Ensign Mario Ramirez Delgado , to explore the area pointed out by the plane . Once the order was received , the CS - 13 sailed speedily toward the area , where the patrtol boat ' s hydro - acoustic means of detection received a clear and precise contact at 900 yards . The seaman operating the sonar , Norberto Collado Abreu , was glued to the equipment , without missing a sound . Then the attack started : three depth charges set to explode at 100 , 150 , and 250 feet , were dropped from the stern , in accordance with the calculated immersion speed of the submarine . Four explosions were clearly detected . The fourth explosion was so strong that the stern of the Cuban ship was submerged and water came in through the hatchway of the engine room . At that time the hydrophones reported a sound similar to a liquid bubbling when it comes from a submerged container that is suddenly opened . It ' s intense whistling slowly decreased . The sounds indicated that the U - boat had been hit . To finish the U - boat off , the patrol boat launched two more depth charges , set to explode at 250 feet . A few minutes later , a dark stain was observed on the surface of the water . A spurt of a black and viscous substance smelling like gasoline came up from the deep . Although there was little doubt that the U - boat had been sunk , Delgado was ordered to take a sample of the contaminated seawater to confirm the victory . But even then it wasn ' t until after the war , when the Allies seized Germany ' s naval records , that proof of U - 176 ' s sinking was found . According to the seized documents , the U - 176 was under the command of Captain Lieutenant Reiner Dierksen , had sunk eleven enemy ships in her career , and was herself sunk with all hands lost . The exploration of the battle area with the hydro - acoustic equipment continued for a short time after the engagement , but no sound was detected . The CS - 13 then joined the convoy again and continued its crossing . Upon arrival in Havana , and after personally informing the Head of the Navy , Delgado spoke on the phone with President Batista , who ordered him to keep absolute silence about what had happened . For some unknown reason , according to Delgado , the sinking of the U - 176 remained a secret to the Cuban public until after the end of the war . In 1946 , Delgado was finally awarded the Meritorious Naval Service Order with Red Badge . Furthermore , Samuel Eliot Morison recognized his success in his work " History of United States Naval Operations in World War II " , where he also praised the ability and efficiency of the Cuban Navy . Samuel Eliot Morison wrote the following about the engagement : German espionage activity in Cuba was minor , despite the country ' s importance to the Allied war - effort , and was eliminated by Allied counter - intelligence before it could really begin . Shortly after the beginning of the war , the Germans began operating a clandestine communications network in South America to collect secret information and safely smuggle it out of the region to Occupied Europe . For Cuba , the Abwehr sent a man named Heinz Lüning to Havana with orders to establish a secret radio station and then transmit the information he collected to agents in South America , where it would then be sent directly to Germany . German espionage . According to author Thomas Schoonover , the plan could have worked , but Lüning was an incompetent spy because he failed to master the very basics of espionage . For example , he was never able to get his radio working correctly , he did not understand how to use the secret ink he was supplied with , and he missed drop boxes . But in spite of all this , after his premature arrest in August 1942 , Allied officials - including President Batista , General Manuel Benítez , J . Edgar Hoover , and Nelson Rockefeller - attempted to fabricate a link between Lüning and the German submarines operating in the Caribbean - by claiming that he was in contact with them via radio - in order to provide the public with an explanation for their failures early in the U - boat campaign . Allied officials elevated Lüning ' s importance to that of a " master spy , " but there is no evidence that he ever came across even a single piece of important intelligence during his time in Cuba . Lüning was found guilty of espionage and executed in Cuba in November 1942 , becoming the only German spy put to death in Latin America during World War II . Ernest Hemingway was living at his home , Finca Vigía , in Cuba when the war began in 1939 . His first contribution to the Allied war - effort without leaving the island was to organize his own counter - intelligence force to root out any Axis spies operating in Havana . Calling it his " Crook Factory , " Hemingway ' s unit consisted of eighteen men , many of whom he had worked with five years before during the Spanish Civil War . The effort was unsuccessful , however , and Hemingway soon turned his attention to fighting the German U - boats operating in the Caribbean Sea . Just three weeks after receiving permission from Ambassador Spruille Braden to form the " Crook Factory , " Hemingway asked Braden for permission to arm his fishing boat , the " Pilar " , for patrols against U - boats off of the Cuban coast . Surprisingly , Baden gave Hemingway permission , and so the latter proceeded with arming the " Pilar " and the crew with machine gun s , bazooka s , and hand grenade s . Hemingway ' s plan was similar to that of the Q - ship idea : He would sail around in what appeared to be a harmless pleasure craft , inviting the Germans to surface and board , and when they did , the boarding party would be disposed of with the machine guns , and the U - boat would then be engaged with the bazookas and grenades . Hemingway ' s patrols against German U - boats turned out to be just as unsuccessful as the counter - intelligence operation was . As the months passed , and as no U - boat appeared , the " Pilar " s patrols turned into fishing trips , and the grenades were thrown into the sea as " drunken sport . " After adding his sons Patrick and Gregory to the crew , Hemingway acknowledged that his U - boat hunting venture had " turned into a charade , " but he never admitted it straightforwardly . Years later , the Cuban naval officer Mario Ramirez Delgado , who sank the U - 176 , said Hemingway was " a playboy that hunted submarines off the Cuban coast as a whim . "