After WWII, believing nuclear weapons had eliminated ground warfare, Truman and his cabinet virtually turned the United States Marine Corps into a police force for the Navy. North Korea's invasion of the South showed him that, in fact, ground warfare was now the warfare of choice, in the eyes of aggressor nations. South Korea was saved only by sacrificing our unprepared citizen soldiers to help the ROKs establish the Pusan Perimeter. The Pusan Perimeter was saved largely by the small group of regular combat troops the Marines had available, and the assault at Inchon possible only because the Marine Reserves were called up.
I've often wondered if Truman ever really understood the opportunistic strategies of Soviet policies and the wishful thinking of his own.
These Marines might have been in the Reserves, driving buses or pumping gas only two months before being thrown into an infantry company and facing and defeating NK veterans here in Seoul. But they did defeat them, and continued to face and defeat them at the Han and at Seoul.
Those who survived that far went on to face ten Chinese divisions at Chosin.
