Which conflict did General Robert E. Cushman lead troops during?

General Robert E. Cushman played a significant role during the Vietnam War as a key Marine Corps leader. He served as the Commanding General of the Third Marine Amphibious Force, where he was involved in critical operations and strategies throughout the war's duration. His leadership was characterized by efforts to adapt to the challenges of jungle warfare and counterinsurgency tactics, which defined the conflict in Vietnam.

The other conflicts listed, while notable in their own right, do not feature General Cushman in a leading capacity. During World War II, he was still a junior officer, and his involvement in the Korean War occurred later in his career with different roles that did not involve leading troops directly. The Gulf War occurred significantly later, after his retirement from active duty. Thus, the Vietnam War stands out as the conflict where he had a direct and impactful leadership role.