Hiryū was an aircraft carrier built for the Imperial Japanese Navy (IJN) during the 1930s. Generally regarded as the only ship of her class, she was built to a modified Sōryū design. Her aircraft supported the Japanese invasion of French Indochina in mid-1940. She took part in the attack on Pearl Harbor and the Battle of Wake Island. During the first few months of the Pacific War, the ship supported the conquest of the Dutch East Indies in January 1942. The following month, her aircraft bombed Darwin, Australia, and continued to assist in the Dutch East Indies campaign. In April, Hiryū's aircraft helped sink two British heavy cruisers and several merchant ships during the Indian Ocean Raid.