What was Cuba's involvement during World War II?
Your question is not very specific, but here are a few facts about Cuba's participation during World War II.
Fulgencio Batista (1901-1973) became the Cuban army chief-of-staff during the mid-1930s, and he was elected President of the nation in the 1940 elections. Cuba was officially a member of the Allied nations during World War II, declaring war on, first, Japan, and then Germany and Italy shortly after the bombing of Pearl Harbor. Although Cuban troops saw little combat during the war, Batista did promote an invasion of Spain that would have included the participation of Cuban troops. Batista's reign as President ended in 1944, but he became Cuba's leader again in 1952 in which he took power in a U. S.-backed coup, serving until Castro's takeover in 1959.
At least seven Cuban ships were sunk by German U-boats between 1942-1944, resulting in the deaths of at least 80 Cuban Marines. In 1943, a Cuban submarine "overturned" a German U-boat near Nuevitas. There were at least four internment or concentration camps located on the island, including one for women at Arroyo Arenas.
A German spy, August Heinz, was apprehended sometime after his arrival on the island in 1941. Information he relayed back to Germany caused the sinking of at least two ships.