What was a global war that lasted from 1939 to 1945, when class of submarines built for the Royal Navy?
British V-class submarine: The British V-class submarine (officially ""U-Class Long hull 1941–42 programme"") was a class of submarines built for the Royal Navy during the Second World War. World War II: World War II (often abbreviated to WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945, although related conflicts began earlier.
i don't know