Throughout which period did the Marines experience the highest total casualties from all causes?

The Southeast Asia conflict, which primarily includes the Vietnam War, is noted for having the highest total casualties for the Marines from all causes. During this period, the USMC faced intense combat operations, with over 14,000 Marines killed and many others wounded, in addition to numerous non-combat-related casualties. The war involved complex guerrilla warfare, heavy enemy engagements, and challenging environmental conditions, which contributed to the elevated casualty figures. This conflict also saw a significant reliance on air and ground support, leading to heavy losses on both sides.

Understanding the historical context of this conflict illustrates the reasons for the high casualty rate. In comparison, while World War II involved significant Marine engagement with major battles such as Iwo Jima and Guadalcanal, the scale of the overall conflict and the different nature of engagements led to a lower total casualty count for the Marines when measured against the extensive duration and combat intensity found in Vietnam.

This context highlights why the Southeast Asia conflict, specifically the Vietnam War, stands as a significant period for Marine casualties compared to other wars in which the U.S. Marine Corps has participated.