The bedrock values of his upbringing, Eisenhower discovered, were also those of West Point's code of Duty, Honor, and Country. The oath of allegiance that he took when he became a cadet signified his acceptance of the civic responsibilities inherent in both codes and remained a cherished moment for the rest of his life. Eisenhower was a good, if not spectacular, cadet, scholar, and athlete, graduating in the upper third of his class in 1915. Of equal importance to the education he received was the friendship of such cadets as Omar Bradley, James A. Van Fleet, and Joseph T. McNarney, all members of the "class the stars fell on," and with men in classes immediately senior and junior to his.

Traits that became valuable years later first emerged at West Point. Eisenhower had the knack of saying the right thing to gain others' cooperation. His strong personality and overwhelming good nature inspired trust. Classmates regarded him as a natural leader who looked for ways to smooth over disputes and organize a group's efforts toward a common goal. As the new second lieutenant of infantry left West Point for his first assignment, it was clear that he was well suited to the world of team play and cooperative endeavor that characterized the Army.

After two years with the 19th Infantry at Fort Sam Houston, Texas, Eisenhower's career accelerated as America began to mobilize for World War 1. Regular officers in the rapidly expanding Army found themselves briskly promoted and given challenging commands. Already a Regular Army captain in 1917, P-Eisenhower was a temporary lieutenant colonel just over a year later. Some of his peers distinguished themselves in France, but Eisenhower never left the United States, a fact that bitterly disappointed him. Instead, he spent the war training troops that others would lead in battle. At the armistice, he was in command of Camp Colt, the Army's tank corps training center on the Civil War battlefield at Gettysburg.

Peace brought demobilization to an Army that had grown to more than two million men. The service contracted to 850,000 in 1919 and then declined to average around 140,000 for the next decade and a half. The officer corps grew smaller as well, and the regulars necessarily returned to their permanent grades. Eisenhower reverted to the rank of captain in June 1920, but he was promoted to Regular Army major a few days later. He held that rank for the next sixteen years of peacetime duty in an Army that appeared to many to have no real function.