Liggett was born on March 21, 1857 in Reading, Pennsylvania. After his graduation from United States Military Academy at West Point, New York as a second lieutenant in 1879, he was assigned to the 5th Infantry, where he served in both the Montana and Dakota territories, as well as Texas and Florida, during which time he reached the rank of captain. Liggett's field service in the American west, the Spanish–American War, and the Philippine–American War honed his skills as a military leader. In 1907, he assumed command of a battalion of the 13th Infantry Regiment at Fort Leavenworth, Kansas. From 1909 to 1914, he served as student, faculty member, and president at the Army War College, receiving a promotion to brigadier general in February 1913. Liggett's services in the Philippines included setting up a staff ride in 1914 to study possible invasion sites on Luzon. He was assisted in this by his aide de camp, Captain George Marshall. The staff ride established that the most likely invasion route would be through the Lingayen Gulf and that this would be all but unstoppable unless the US dramatically increased its army and navy forces in the Philippines. In 1941, the Japanese invaded through the Lingayen Gulf, as the United States did in turn in 1945.
Liggett wrote about his war time experiences in A.E.F.: Ten Years Ago in France. In 1930, Congress passed a law permitting World War I generals officers to retire at the highest rank they had held, and Liggett was promoted to lieutenant general on the retired list. He died December 30, 1935 in San Francisco, California and is interred at the San Francisco National Cemetery. His grave can be found in the officers section 3, plot 1.
Honors and awards
Military honors
;American awards ;Foreign awards
Army Distinguished Service medal citation
;Citation
Other honors
In his honor, the United States Army named a base on California's central coast, Fort Hunter Liggett. Liggett Hall is a regimental-sized barracks building constructed at Fort Jay on Governors Island in New York Harbor. Completed in 1930, it was thought to be the largest building constructed by the U.S. Army and was the largest structure built under the supervision of the U.S. Army Quartermaster Corps. It was superseded by the Pentagon, constructed by the U.S. Army Corps of Engineers in 1943. The was a passenger ship that was transferred to the Army and renamed Hunter Liggett in February 1939. The ship transported personnel and supplies until May 27, 1941, when she was turned over to the Navy. Converted to Navy use at Brooklyn Navy Yard, she re-commissioned as AP-27 June 9, 1941, and then again reclassified APA-14 February 1, 1943 for the United States Coast Guard.