William Lassiter (September 29, 1867 – March 29, 1959) was a career officer in the United States Army.

A native of Petersburg, Virginia, Lassiter graduated from the United States Military Academy in 1889 and began a career in the Army's Field Artillery Branch.

He subsequently served on the West Point faculty and carried out several years of temporary duty with the Inspector General, including postings to Cuba and the Philippines.

[4] In March 1898, Lassiter's regiment moved to Galveston, Texas, in preparation for overseas service during the Spanish–American War.

[4] After his service in Cuba, Lassiter was assigned to West Point as an assistant instructor of tactics, where he served from August 1898 to July 1901.

[4] He also served as a member of the board that tested cannons and ammunition and made procurement and fielding recommendations.

He then performed temporary duty at the Office of the Inspector General in Washington, D.C., and member of the staff at the War Department.

[4] In October 1911, Lassiter was assigned as a member of the U.S. Military Mission which was invited to observe army education and training in Germany, France, and England.

In August 1917, four months after the American entry into World War I, he received a temporary promotion to brigadier general.

Lassiter was then assigned to command Base Section Number 3 and all American troops in England, and he served until being reassigned in October.

[4] As the American Expeditionary Forces (AEF) continued to arrive in France during 1918, Lassiter was reassigned as chief of artillery for I Corps, and simultaneously oversaw the final organization and training of the 66th Field Artillery Brigade prior to its entry into combat.

In August 1918, Lassiter was assigned as chief of artillery for IV Corps, where he took part in the Battle of Saint-Mihiel in September.

[4] In October 1918, Lassiter was assigned as chief of artillery for the Second Army, and he served during fighting in the Toul area until the Armistice that ended the war.

The citation reads: The President of the United States of America, authorized by Act of Congress, July 9, 1918, takes pleasure in presenting the Army Distinguished Service Medal to Major General William Lassiter, United States Army, for exceptionally meritorious and distinguished services to the Government of the United States, in a duty of great responsibility during World War I.

His energy and sound judgment influenced greatly the successful operations of his commands on the Vesle, at the St. Mihiel salient, and in the Toul sector.

[4] From January to June 1926, Lassiter was president of the Tacna-Arica Arbitration Plebiscite Commission, succeeding Pershing in an international effort to mediate a longstanding territorial dispute between Chile and Peru.

[4] He then performed temporary duty at the U.S. State Department in Washington, D.C., where he completed the activities of the plebiscite commission and submitted its final report.