Gallagher joined the Navy and rose to the rank of Lieutenant Commander. He returned to Boston after the war and resumed his coaching duties in 1946. Gallagher was named as the New England hockey coach of the year in 1948 and shortly afterwards became one of the driving forces behind the formation of the Beanpot an annual ice hockey tournament held between the four Boston-area programs. In 1955 he was named as Athletic Director for NU and over the next twenty one years worked to raise the profile of the school's programs. In that time he was also on the NCAA Ice Hockey Rules Committee and the USOC for the 1956 Winter Olympics.