Edgar F. Puryear, Jr. 19 Stars: A Study in Military Character and Leadership:
Williamson Murray and Allan Millet, A War to Be Won
General Eisenhower followed the same practice with his Army commanders. He gave them their job and left them alone; with responsibility for millions of men and billions of tons of material he had to. By contrast, the British chiefs maintained daily contact with their field commanders and interfered consistently in tactical plans.
Max Hastings Inferno:
Coming into the war last, the Americans experienced their own weaknesses. In 1939 the US Army had ranked seventeenth in the world. As compared to the Germans, who by 1939 had been preparing themselves for war for six years, the American's had barely three years before their troops were committed to combat. Consequently, many units that fought in Normandy displayed a depressing lack of tactical sophistication. Nevertheless, most US formations exhibited greater adaptability than their British counterparts, and their learning curve was steady and steep. Such improvements owed much to the flexibility of a citizen army, as well as to the ruthlessness with which Eisenhower sacked senior officers who failed.
[Under Eisenhower in North Africa in 1943] the most visibly incompetent American officers were replaced with a ruthlessness the British might had profitably emulated.