He was commissioned a Second Lieutenant, May 20, 1898 in the Signal Corps and eventually reached the rank of Major General, July 9, 1935.
Kilbourne served in the Philippine-American War as a second lieutenant in the campaign which captured Manila and included operations in Cavite, Laguna and Bulacan Provinces. He served in the Boxer Rebellion in China and the relief of the Allied legations in Peking and in operations in South Sulu. Kilbourne had five tours of duty in the Philippines. He was responsible for much of the military development of the island fortress of Corregidor. During his third assignment there, from 1908 to 1913, he established the first artillery garrison on Corregidor. In later Philippine duty in the late 1920s, Gen. Kilbourne initiated the elaborate tunnel system of Corregidor (Malinta Tunnel) which served American troops during the early stages of World War II and enabled Gen. MacArthur's troops to resist as long as they did in the face of the overwhelming odds in favor of the Japanese.
He was assigned to duty with the General Staff from 1911–1913 and again in 1915. He arrived in France on January 1, 1918 for service in World War I where he served on both the British and French fronts for a short period and then returned to Washington in March. While on an inspection tour, he lost the vision in his right eye in the explosion of a trench mortar shell. He returned to France in May 1918 with the 89th Division, continuing with that unit until October 6, 1918. He commanded the 36th Heavy Artillery Brigade and the 3rd Infantry Brigade during the remainder of his service in France and Germany.
He was the head of the U.S. Mission inspecting the coastal defenses of Europe and Turkey and returned to the U.S. in May 1919 to serve on the faculty of the Army War College from, 1920 - 1924. He later served as one of the directors of the college. He was Commandant of Boston Harbor from 1924–25 and Executive Assistant to the Chief of Coast Artillery from 1925 - 1928. In 1928 he commanded the 2nd Infantry Brigade, 1st Division until 1929 after which he commanded the Coast Artillery District of Manila and Subic Bay from 1929–1932 and served in the War Plans Division in Washington D.C. from 1932 - 1934. He commanded the VI Corps area and 2nd Army, 1936.
Kilbourne retired from the Army in 1936 as a Major General. He died on November 12, 1963, and is buried in Section 3 of Arlington National Cemetery.
Awards and honors
During his career in the Army, Kilbourne received numerous awards including:
- Medal of Honor for "distinguished gallantry at Paco Bridge, Philippine Islands, February 5, 1899
- Distinguished Service Cross for "extraordinary heroism in action" near Thiacourt, France, September 12, 1918
- Distinguished Service Medal "for services in 89th Division and 36th Artillery Brigade"
- Croix de Guerre (France) for "reconnaissances preparatory to assault on the St. Mihiel Salient," # Legion of Honor; Philippine and Victory Medals.
Within a range of 250 yards of the enemy and in the face of a rapid fire climbed a telegraph pole at the east end of the bridge and in full view of the enemy coolly and carefully repaired a broken telegraph wire, thereby reestablishing telegraphic communication to the front.