Why did Eisenhower fight in World War 2 and not in World War 1?

Eisenhower led troops in World War Two because he was the best officer in the Army at that time to do that. He was a superb tactician but he was also a top-notch diplomat, both of which were needed to help all the other Allies work with each other in an effective manner.

He did not fight in World War One because he had early, Excellent training in tank warfare. So he was ordered to spend the year of the US involvement in World War One training soldiers in tank tactics.