The increasing number of American troops in the European theatre (from five out of ten divisions at D-Day to 72 out of 85 in 1945) made it a political impossibility for the Ground Forces Commander to be British. After the end of the Normandy campaign, General Eisenhower himself took over Ground Forces Command while continuing as Supreme Commander, with Montgomery continuing to command the 21st Army Group, now consisting mainly of British and Canadian units. Montgomery bitterly resented this change, although it had been agreed before the D-Day invasion. Winston Churchill had Montgomery promoted to Field Marshal by way of compensation.