With the army expanding for
World War I, in October 1917, Winn was assigned to
Camp Dix, New Jersey as the post's inspector general. In December 1917, he was promoted to the temporary rank of
brigadier general. In January 1918, Winn sailed for France after he was assigned as inspector general for the
Services of Supply (SOS) of the
American Expeditionary Forces (AEF). He served in this position until September, when he joined the
3rd Division at the start of the
Battle of Saint-Mihiel. Later that month, he was transferred to the
4th Division as commander of its
7th Infantry Brigade, which he led during the
Meuse–Argonne offensive. In early October, Winn assumed command of the
73rd Infantry Brigade, one of two infantry brigades of the
37th Division. He was hospitalized for illness from mid-October until November 15, four days after the
Armistice with Germany which ended the war, when he took command of the
157th Infantry Brigade, part of the
79th Division. In addition to commanding this brigade, Winn acted as division commander on several occasions. After completing his
occupation of the Rhineland duty in May 1919, Winn was assigned to the Cavalry Efficiency Board, which made recommendations on the Cavalry Branch's post-war staffing, equipping, and training. In October, he returned to his permanent grade of colonel, his brigadier general's rank only being for the duration of the war. In December, he was assigned as commander of the
2nd Cavalry Regiment at Fort Riley. He retired from the army, after well over 30 years of service, in July 1922, and resided in
Berkeley, California. In 1930, the
U.S. Congress enacted a law permitting the general officers of World War I to retire at their highest rank, and Winn was promoted to brigadier general on the retired list. Winn died at the age of 76 inn Berkeley on January 24, 1940. He was buried at
West Point Cemetery. ==Awards==