William Corcoran Eustis (July 20, 1862 - November 24, 1921) was a captain in the United States Army and the personal assistant to which General of the Armies during World War I, who was was a senior United States Army officer, that had a nickname of "Black Jack"?
John J. Pershing General of the Armies John Joseph "Black Jack" Pershing (September 13, 1860 – July 15, 1948) was a senior United States Army officer. His most famous post was when he served as the commander of the American Expeditionary Force (AEF) on the Western Front in World War I, 1917–18.
Jack Agnew John "Jack" Agnew, United States Army (January 2, 1922 – April 8, 2010) was a United States Army private first class in World War II, a member of the Filthy Thirteen, whose exploits inspired the novel and film "The Dirty Dozen".