The 5th Marine Division was a United States Marine Corps ground combat division which was activated on 11 November 1943 at Camp Pendleton, California during World War II. The 5th Division saw its first combat action during the Battle of Iwo Jima in 1945 where it sustained the highest number of casualties of the three Marine divisions of the V Amphibious Corps. The 5th Division was to be part of the planned invasion of the Japan homeland before Japan surrendered. Assault troops of the 5th Division were included in the Presidential Unit Citation awarded to the V Amphibious Corps for extraordinary heroism on Iwo Jima from 19 to 28 February 1945. The 5th Division was deactivated on 5 February 1946.

The Battle of Iwo Jima was a major battle in which the United States Marine Corps (USMC) and United States Navy (USN) landed on and eventually captured the island of Iwo Jima from the Imperial Japanese Army (IJA) during World War II. The American invasion, designated Operation Detachment, had the purpose of capturing the island with its two airfields: South Field and Central Field.