In his position as lecturer on Military Science and Tactics, Morize trained students on trench warfare and machine gun combat at Fresh Pond in Cambridge, MA, and was involved in campus events about the war.

As Morize prepared to return to France at the end of World War I, Harvard president A. Lawrence Lowell invited him to stay on as a professor of French literature and culture.

On a vacation in France after directing the 1939 French summer school at Middlebury College, Morize found himself suddenly caught up in the second World War.

[12] He served in the French Ministry of Information until France was overrun by the German army and the Vichy government was installed.

He kept about a day ahead of the tide of the German army as he made his way to Lisbon, Portugal, to catch a clipper back to the United States.

[15] He returned to his professorial duties but remained active in the Harvard and local Boston community, advocating for relief measures for refugees.

[20] However, his wife took him to court in Suffolk County, Massachusetts, seeking compensation because she claimed Morize had abandoned her by traveling to and deciding to stay in France after his retirement.