Marcus was a tough Brooklyn street kid who attended West Point and then law school. In World War II, Marcus rose to the rank of Colonel in the U.S. Army, where he helped draw up surrender terms for Italy and Germany. While serving in the occupation government in Berlin, he was responsible for clearing out the Nazi death camps, and then as chief of the War Crimes Division, where he helped arrange the Nuremberg trials.
Seeing the Jewish suffering first-hand, Marcus became a committed Zionist, and in 1947 he volunteered to help secure the Jewish settlements which were under attack from hostile Arabs.
Marcus designed a command structure for Israel's new army and wrote manuals to train it. His most famous achievement was ordering the construction of the "Burma Road," a winding mountainous path which allowed Jewish convoys to reach Jerusalem and relieve the Arab siege.
Tragically, on the day that the war's cease-fire took effect, Marcus was mistakenly shot by a Jewish guard.
His story became the subject of a movie, Cast a Giant Shadow, starring Kirk Douglas, John Wayne, Frank Sinatra and Yul Brynner.