In addition to practicing law in Albany, New York, he served in the United States Army during the Spanish–American War.

[5] In July 1898, Westcott began a military career when he enlisted in the United States Army for the Spanish–American War.

[7] In February 1901, he joined the New York National Guard's 10th Separate Infantry Battalion as a private in Company A.

[7] In 1917, the U.S. military expanded in anticipation of U.S. entry into World War I, and America entered the conflict in April 1917.

[7] Westcott played a prominent role in the New York National Guard's wartime activities, and he received appointment as assistant adjutant general and promotion to lieutenant colonel in June 1918.

[7] Smith appointed him to a full two-year term in January 1925, and Westcott continued to serve until his death.