Complex sentence: During the Korean War the Navy placed Dufek in command of the aircraft carrier from 17 January 1951--6 May 1952, then of the naval installation on Kwajalein in the Pacific and, finally, the Naval Air Station Whidbey Island in Oak Harbor, Washington.
Split into simpler sentences: During the Korean War the Navy placed Dufek in command of the aircraft carrier from 17 January 1951--6 May 1952. Dufek was then given command of the naval installation on Kwajalein in the Pacific and, finally, the Naval Air Station Whidbey Island in Oak Harbor, Washington.