Sanno took part in the
Spanish–American War as acting inspector general of the
Department of the Missouri from April 20, 1898, to June 30, 1898, and acting inspector general of the
Department of Dakota and the
Department of the Lakes from July to December 1898. He was promoted to
lieutenant colonel in the 4th Infantry in August 1898. During the
Philippine–American War, Sanno commanded the
4th Infantry in the
Philippines. From June to July 1899, he commanded 2nd Brigade, 1st Division,
Eighth Army Corps at
Las Piñas. During his Philippines service, Sanno took part in engagements against Filipino insurgents at
La Loma Church on March 24, 1899, near Taytay on June 3 and 4, 1899, and near
Dasmariñas on June 19 and 20. Sanno was on sick leave in
Japan from July to November 1899, and in Manila from November 1899 to January 1900. He was promoted to
colonel in the
18th Infantry in December 1899. After being assigned to command the 18th Infantry, Sanno served from January to August 1900 as a member of the army board in Manila that audited wartime claims against the United States. After returning to the United States and going on sick leave in late 1900, he was on duty at
Plattsburg Barracks, New York, from February to August 1901 as commander of the
27th Infantry. He commanded the regiment until July 1903, including service at
Fort D. A. Russell,
Wyoming and at Camp Bumpus, Philippines. In November and December 1901 and March to April 1902, Sanno was commander of the Department of Colorado. Sanno requested retirement in July 1903. He was promoted to
brigadier general on July 30, 1903, in recognition of his 40 years of service, and he retired on July 31. ==Commendations==