What was the peak strength of the USMC during World War II?

The peak strength of the USMC during World War II was actually 485,113 Marines. This figure represents the maximum number of personnel in the Marine Corps at any one time during the war, which was a significant increase from pre-war levels. The Marine Corps expanded rapidly to meet the demands of the war effort, undertaking numerous amphibious assaults across the Pacific Theater. This level of personnel strength was vital in enabling the USMC to conduct sustained operations and successfully carry out its missions during the conflict. Understanding the scale of this expansion is crucial, as it highlights the critical role the Marine Corps played in the broader military strategy during World War II.