Eisenhower, however, was more than just Marshall's agent. The Supreme Allied Command in Europe would never have worked without Eisenhower, for he virtually invented the concept of Allied unity of command and persuaded the British to accept it in lieu of the committee system to which they were accustomed. His personal qualities played a large part in gaining acceptance of a much more centralized and powerful Allied command than had existed in World War 1. Men instinctively trusted him, and his measured approach to command reinforced a conviction that he was an honest broker whose central purpose was the defeat of the enemy, rather than the pursuit of any national agenda. Eisenhower, in short, was the essential man in the coalition against Hitler.

The job of Supreme Commander lay in the future when he arrived in England. At first, he was only the commander of American troops in the European Theater, and had the immediate task of assembling the means with which to pursue the war. Few combat-ready American soldiers were in the United Kingdom at the time, and there was a shortage of ships, landing craft, weapons, ammunition, air power, and solid intelligence about the enemy. Eisenhower devoted himself to energizing his staff, building a solid relationship with the British ally, and managing Operation BOLERO, as the buildup of resources for the ultimate invasion of Europe was dubbed. In November of 1942, incident to the decision to land British and American troops in North Africa (Operation TORCH), the Combined Chiefs of Staff appointed Eisenhower Commander in Chief, Allied Forces, for that invasion.

Both Marshall and Eisenhower had resisted the decision for TORCH because it was a diversion of resources from the invasion of Europe, an operation they insisted was far more important. Nonetheless, a confluence of political and military considerations on both sides of the Atlantic argued in favor of TORCH, and their combined weight overwhelmed War Department objections. American military plans had never envisioned an invasion of Europe before 1943, except in the most exceptional circumstances, but President Franklin D. Roosevelt had concluded that he simply could not wait that long for American soldiers to begin fighting the nation's chief enemy. He accordingly directed Marshall to find some way to come to grips with the Germans in 1942. At the same time, American commanders in the Pacific were casting covetous eyes on the men and equipment BOLERO was concentrating in Europe. Unless Eisenhower made some use of that military power soon, Marshall knew, MacArthur and the Navy would submit