0
There were a couple of million American troops eventually in England in the build-up to D-Day, so they had bases all over. Primarily the American bases were in the south and west of England. When Americans began to arrive the British Army was already in southeast England, where they had taken up positions after Dunkirk, awaiting the German invasion. This actually had important consequences. The relative positions of the armies in England meant that when they boarded ships to head for France, the British would be on the left and the Americans on the right, and they would land in France like that, and remain in those relative relationships until the war was over. The only alternatives were to try to move millions of troops around in England before setting off to invade France (unthinkable with the secrecy and security surrounding D-Day preparations) or to try to cross the paths of the blacked-out invasion fleets in the dark, on the English Channel on the night before the invasion, impossible without running risks of multiple collisions. So the British would be on the left, and the Americans on the right. Why did this matter? Because the short route to Berlin was on the left, and the only good tank country. The Americans had many, many more tanks than the British, and the entire American Army was motorized - if there was a breakthrough, there was a vehicle for every man to ride. And the American Army was only going to get bigger, as more millions of Americans, for whom there was no room in England, followed on from the states. The British had no replacements whatsoever for their army, and once they began losing men, their army was going to shrink. Nevertheless the much less mobile British Army got the good route to Berlin, though they lacked the strength or mobility to make the most of the chance. And all because of the relative locations of the bulk of their forces in England.
There were also dozens of American air bases in England, hosting about twenty-five heavy bombardment groups, plus fighter groups of the 8th Air Force, and the medium bombers and fighter-bombers of the 9th Air Force. More than two million men served in the 8th AF.
