After his unit was federalized for service in the Spanish–American War, Gulick served in Florida and Cuba before obtaining an Artillery commission in the regular army and assignment to the 47th U.S. Volunteer Infantry Regiment.

He was educated in the public schools of Goldsboro, and attended courses in engineering at several universities prior to embarking on a full-time military career.

[1] At the start of the Spanish–American War, Gulick's National Guard unit was federalized, and he served in Florida and Cuba, including assignment as quartermaster and ordnance officer for 1st Brigade, 2nd Division, Seventh Army Corps.

[1] Gulick took part in several battles and skirmishes, commanded the 21st Coast Artillery Company and the Army post at Gubat, and was promoted to the brevet rank of major for heroism in action near Bulusan on August 10, 1900.

[1] In November 1911, Gulick was assigned as military attaché in Chile, and a special act of Congress enabled him to serve as an instructor and advisor on coastal defenses as a major in the Chilean army.

[1] In April 1916, Gulick was assigned to Fort Oglethorpe, Georgia, as commander of a Coast Artillery battalion, and also assisted in the organization and operation of an officers' training camp created as part of the pre-World War I Preparedness Movement.

[1] In May he was ordered to El Paso, Texas with two batteries from his battalion, and assigned to security duty on the Mexican border during the Pancho Villa Expedition.

[1] Gulick was promoted to major in July 1916 and assigned to the 5th Provisional Coast Artillery Regiment, with duty in Del Rio, Texas.

[1] He took part in the St. Mihiel and Meuse-Argonne offensives, and was a recipient of the Army Distinguished Service Medal and the French Legion of Honor (Officer).

[3] After his graduation, he served at the Fort Hancock, New Jersey, proving ground as executive officer, and then commander of the coast artillery defenses at Sandy Hook.

[5] In 1937 he was assigned to command the Third Coast Artillery District, based at Fort Monroe, where he remained until reaching the mandatory retirement age of 64 in November 1938.