The advent of World War I caused a shortfall in the numbers of senior officers and non-commissioned officers needed for an expanding manpower base and promotions were accelerated to meet the need. Eisenhower was promoted to captain at the start of the war, just two years after being commissioned, and he was subsequently temporarily promoted to major and then lieutenant colonel just prior to the War's end in 1918. He was reverted to his permanent rank of captain in 1920 and promoted to major that same year (5 years after being commissioned). While 16 years as a major appears quite long, Eisenhower was promoted to lieutenant colonel with his West Point class.
I wouldn't consider his career as being "stagnant" during the 1920s and 30s as he had a number of high profile assignments prior to his promotion to lieutenant colonel: tank battalion command, infantry regiment executive officer, graduation from both intermediate and top level school, Battle Monuments Commission, manpower and industrial mobilization planner at Army Headquarters, and Personal Assistant to MacArthur.
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