The 2d Division returned to Fort Lewis in 1955, but its stay was to be short. In 1956 there was a three-way divisional switch. The 2d was moved to Alaska to replace the 71st, which arrived at Fort Lewis only to be deactivated. In September, the 4th Infantry Division arrived for a permanent stay after five years in Germany. It trained several cycles of recruits; and then, in April 1957, the 4th was reorganized as a Pentomic Combat Division.

Meanwhile, Fort Lewis continued to expand its area of responsibility. Vancouver Barracks, once the military capital of the Pacific Northwest, became a Fort Lewis subpost in 1958. The 62-acre post faced on the Columbia River across from Portland, Oregon, and was historically important during Hudson Bay Company days and when the Oregon Territory was being settled. Nearby Camp Bonneville, a 3,800-acre primitive training area, was frequently used by Fort Lewis troops.

In 1959 the 4th Division was selected as a component of the Strategic Army Corps (STRAC), and assigned to the XVIII Airborne Corps. Later, it was assigned to III Corps while it trained at Fort Lewis. Then, on 1 October 1963, it was again reorganized under the ROAD (Reorganizational Objective Army Division) concept.

As a result of the Berlin Crisis of 1961, the 32nd Infantry Division was called to active duty. It was a post resident on into 1962.

In September 1964, Sixth Army established its NCO Academy at Fort Lewis. Teaching nine classes a year, the Academy graduated about 400 students annually.

Fort Lawton, on Magnolia Bluff in Seattle, constructed in 1897, became a subpost in 1965. It was a busy processing and overseas shipment point during World War II and the Korean War, but has now reverted to a Reserve Center, effective 1981.