St. John’s has a long tradition of involvement with the military. It was founded with a general program of study in the liberal arts, but St. John’s was a military school for much of the late 19th century and early 20th century. It ended compulsory military training with St. John’s alumnus Major Enoch Garey’s accession as president in 1923, so students could concentrate on getting a bachelor’s degree. He replaced the cadet corps with a voluntary ROTC program established to supply officers with a broader range of experience than was in those days available at military colleges. In September 1924 Garey brought the nation’s first Naval Reserve program to St. John’s as a pilot program to test the scheme for the Navy, (The US Naval Academy in Annapolis would not begin issuing bachelor’s degrees until 1933). Program graduates were appointed as ensigns in the Naval Reserve. This initial program’s success was enough to convince the Navy to establish six full-scale NROTC programs at Northwestern, Harvard, Yale, UC Berkeley, the University of Washington and Georgia Institute of Technology in 1926. But despite St. John’s successfully pioneering the entire NROTC movement, student interest waned, the voluntary ROTC disappeared in 1926 with Garey’s departure, and the Naval Reserve unit followed by 1929.

A good number of St. John’s students are among the veterans of the wars of the past century and over the years, some Johnnies have pursued military careers after graduation. The College has always welcomed Active Duty members and veterans as students, both in its undergraduate program and in the Graduate Institute. Today, St. John’s provides the maximum financial support possible under the Yellow Ribbon Program, a federal educational assistance program available to post-9/11 active duty veterans and their dependents. Between funding from the Veterans Administration and grants from St. John’s, all tuition and fees are covered for these students. Several students are enrolled under this program, and its financial commitment to this program over the last few years is among the highest in the state of Maryland, despite its small size.

The Great Books program which forms the core of the education at the College developed during World War One. Many scholars and politicians believed that the horrors of the war had threatened the West’s core beliefs and made urgent the task of educating Americans about the ideals on which Western Civilization had been constructed. The federal government encouraged colleges and universities to begin "war-issues courses" for the student soldiers headed overseas. John Erskine, a brilliant Columbia professor used this course to advance his own inter-disciplinary approach to education using classic texts from the Western Canon. The end of the hostilities found him at the American University in Beaune, France organizing Great Books courses for soldiers waiting to return stateside. Erskine’s experiences seeing how these soldiers read these books so directly and enthusiastically, confirmed for him his belief in this way of teaching learning. He returned to Columbia and established a variation on the Great Books program that still exists today. It was imitated and refined at University of Chicago and the University of Virginia, before being established as the sole curriculum by Scott Buchanan and Stringfellow Barr at St. John’s in 1937.