It is my understanding that more Marines died in Vietnam than in WWII.
The Marines were very small, and their major influence was the doctrine of amphibious landings. Of 248 US amphibious landings in WWII, 48 were conducted by the Marines. 200 were conducted by the Army.
Not exactly
World War 2
Dead Wounded
19,733 68,207
Viet Nam
13,095 88,594
Source: http://www.history.navy.mil/faqs/faq56-1.htm
Viet nam wounded casualty figure may reflect more complete record keeping during that conflict.