General Dwight David Eisenhower did the impossible. No, not the successful D-Day landing. Or the subsequent march to Germany. His "impossible dream"—come true—was to keep the Allies(?) from killing each other long enough to kill the bad guys!
And General Eisenhower had a secret: "Allied commands depend on mutual confidence; [this confidence] is gained, above all, through the development of friendships."
Armchair General (May 2008) traces the origins of this mystical Eisenhower trait: "Perhaps his most outstanding ability [at West Point] was the ease with which he made friends and earned the trust of fellow cadets who came from widely varied backgrounds; it was a quality that would pay great dividends during his future coalition command."