The Armory was vacated in 1941, when Maine’s National Guard troops came under the control of the federal government. For a brief time, a caretaker was the lone occupant of the building. City officials ultimately decided to open the armory to house soldiers, sailors, and marines who were temporarily stranded in Portland. During one two-month period, over 4,000 men took advantage of the facility for overnight stays.
In 1942, the United States Navy took control of the armory and used it as a recreation center for the duration of World War II. At the close of the war the building once again served multiple purposes as a home to the National Guard's citizen soldiers, a civic auditorium, and as the city's public bathhouse. In 1962 the Armory was taken over by the city of Portland for conversion into a waterfront parking lot. Before this transformation could take place, the armory was sold to State Paper Company for use as a warehouse.
The armory was finally purchased in 1984 for conversion into a hotel. The Portland Regency Hotel opened with 95 rooms in 1987, complementing Portland's restored Old Port.
The exterior of the armory was preserved intact, with the exception of the skylight windows on the upper floors. Many of the original architectural elements now create unique features within the guestrooms. Highly detailed fireplaces and turret windows bring a special ambiance to this historic hotel.