Walter was born on the 29th of September 1881, in Haverhill, Massachusetts, and after high school he attended Harvard College. In 1904 he joined the US Marine Corps and graduated from college, commissioning as a Second Lieutenant and soon was assigned to the Norfolk Navy Yard. He deployed to Cuba in support of the Banana Wars as part of the Marine detachment on board the USS Massachusetts. By 1909, Walter was a First Lieutenant and sailed to the Philippines and China, where he remained until 1912. He was a Captain when he deployed to Vera Cruz in support of the Mexican Campaign and it was his actions there that would earn him the Medal of Honor. The citation reads:

For distinguished conduct in battle, engagements of Vera Cruz, 21-22 April 1914. Capt. Hill was in both days' fighting at the head of his company, and was eminent and conspicuous in his conduct, leading his men with skill and courage.

Much of Walter’s later life is not well documented, other than he served in France during World War 1 and was recalled to service for World War 2. He retired from the Marine Corps as a Brigadier General after more than 36 years of service. Walter Newell Hill died at the age of 73 on the 29th of June 1955, and he is buried in Arlington National Cemetery with his wife Mary: Section 6, Lot 9646-C