On 15 May 1943, the Cuban freighters "Camaguey" and "Honduran Hanks" were being escorted by three small Cuban Navy submarine chasers from Sagua La Grande to Havana. The convoy was nearing Havana in the Gulf of Mexico when an American reconnaissance aircraft spotted a German U-boat. The aircraft dropped a smoke float over , and the Cuban submarine chaser —under Second Lieutenant Alférez Delgado—picked up the enemy craft with sonar. "CS-13" attacked with depth charges and quickly sank the U-boat which killed all of her crew.