"L-Day" generally refers to April 1, 1945, the day Operation Iceberg, the amphibious Invasion of Okinawa, began. L-Day is sometimes mistaken for meaning "landing day," though it actually refers to a D-Day. Since the best known D-Day is June 6, 1944, the day on which the Battle of Normandy began, the planners of the Battle of Okinawa opted to avoid the term.
Because of the significance of the battle of Normandy, many planners of later military operations sometimes used a different letter to designate the day on which a combat attack or operation is to be initiated. For example, Douglas MacArthur's invasion of Leyte began on "A-day", the Allied proposed invasions of Japan would have begun on "X-Day" (Kyūshū, scheduled for November 1945) and, "Y-Day" (Honshū, scheduled for March 1946).