From November 1887 to August 1888, Hale taught military photography at the Engineer School of Application.

[3] In September 1888, he won a gold medal for rifle marksmanship in the U.S. Army competition at Fort Niagara, New York.

[3] In September 1889, he took a leave of absence to supervise the construction of the South Broadway line in Denver, Colorado, creating the first successful electric railway there.

[4] Still living in Denver, Hale joined the state militia in May 1897 as lieutenant colonel in the 1st Infantry Regiment, Colorado National Guard.

[7] The First Colorado, like many other state militias, was sworn into service at the beginning of the Spanish–American War in April 1898, with Hale as colonel of U.S.

The First Colorado secured the American left flank during the Battle of Manila, capturing Fort San Agustin, and raising the first American flag over the city's fortifications; his excellent leadership secured Hale a promotion to the rank of brigadier general of volunteers in command of the 2d Brigade, 2d Division, Eighth Army Corps.

In addition, a prominent plaque in his honor was placed on the south side of the Colorado State Capitol Building, in Denver.