His first conflict was the Spanish–American War serving in the 7th Infantry, and fighting in the Battle of San Juan Hill and Siege of Santiago.

Preston was involved in the Quartermaster Corps and the Pay Department until the outbreak of World War I, serving a couple of years in France.

After a four-year tenure and brief stationing at Fort Sam Houston, he retired from the army in 1936 and entered the banking industry in San Antonio.

Preston was them with the regiment in Tampa, Florida, until June 4, 1898, when he fought in the campaign against Santiago, and the Spanish–American War to August 1898.

[4] For his service in the war, he received the Silver Star "for gallantry in action against Spanish forces at Santiago, Cuba, July 1, 1898.

Next Preston was stationed in Aparri, Cagayan Valley as a drill sergeant and battalion adjutant to June 5, 1901.

[6] On June 30, 1901, Preston joined the regiment at Nueva Caceres and later Daet, Camarines Norte and in the field, to September 12, 1901, when he returned to the United States.

He was briefly an umpire at West Point in Kentucky, and Fort Riley, in Kansas, from September 26 to October 31, 1903.

He was adjutant and statistical officer of the Southwestern Division Rifle and Pistol Competitions and in command of Fort Brown, Texas, from August 21, 1906, until September 25, 1906, when the post was abandoned.

[6] Preston finished his time in the Philippines at Cuartel de Espana on June 15, 1909, and returned to the United States.

On October 31, 1912, he left the fort and moved to San Antonio, where he led the Quartermaster Corps there from November 1 to February 10, 1913.

[5] Preston was stationed at Fort Sam Houston, Texas, as G-3 and then Chief of Staff, 8th Corps Area, from September 11, 1923, to October 1, 1926; when he was assigned to 1st Infantry.

He remained at the fort from June 28, 1927, to November 22, 1928; when he moved to Washington, D.C., and was made Executive, Office of The Inspector-General, on Nov. 24, 1928.

When the attempt failed, Preston reverted to the permanent rank of colonel and was stationed at Fort Sam Houston, Texas, as the Eighth Corps Area civilian components officer from Dec. 1, 1935, to Nov. 30, 1936.