War Plan Orange
In 1937, Japan invaded China and in September 1939, Germany invaded Poland. As a precautionary measure, the 295th and 296th Infantry Regiments of the Puerto Rican National Guard, founded by Major General Luis R. Esteves, were called into Federal Active Service and assigned to the Puerto Rican Department in accordance with the existing War Plan Orange. That same month, Marxuach joined the United States Army and on October 15, 1940, was commissioned a second lieutenant. He was assigned to the 295 Regiment at Camp Tortuguero in Puerto Rico and soon after was reassigned to 296th Infantry Regiment.