The Battle of Iwo Jima was the largest all-Marine amphibious force in World War II (Okinawa was a larger amphibious invasion, but was a combined Army-Navy-Marine operation) and one of the few where American casualties exceeded the Japanese (26,000 American dead and wounded compared to 18,000 Japanese dead, 2,000 missing, and 1083 prisoners of war.) One in three Americans who fought on Iwo Jima were casualties. The entire Japanese garrison was annihilated.
Kuribayashi upset the Allies’ timetable by approximately two weeks, delaying the invasion of Okinawa to April 1.