Gibbs agreed, and formally asked Major General Irwin McDowell, who replaced Wright as commander of the Department of the Pacific, to request authority to recruit additional troops for military operations in Oregon.

On 31 August 1864, Gibbs and McDowell sent a joint letter to the War Department in Washington, D.C. requesting permission to recruit a new infantry regiment and cavalry replacements.

The state's pro-union newspapers including The Oregonian, the Oregon Statesman, and the Jacksonville Sentinel all encourage young men to join the new regiment.

Most companies spent their time in garrison duty at small posts in eastern Oregon, southeast Washington, and southern Idaho.

[3][4] While scouting sixteen miles from Camp Wright on the Selvies River, near present-day Burns, Captain Loren L. Williams and a party of twenty Oregon infantrymen from Company H were ambushed by a band of hostile Native Americans.

Williams and his troops fought a harrowing retreat back to Camp Wright, defending themselves for about fifteen hours before they reached safety.

[3] In the summer of 1865, Lieutenant Cyrus H. Walker and the men of Company B were responsible for disarming friendly Native Americans and guarding numerous wagon trains as they crossed southern Idaho.

[3] Lieutenant William Grant and his detachment accompanied David P. Thompson and his government survey team through central Oregon as they plotted the Deschutes Meridian, a north–south line extending from the Columbia River to the California border.

In another party, Lieutenant John M. McCall led a detachment of forty-eight men responsible for escorting State Surveyor Byron J. Pengra and his assistants as they surveyed the route of the Oregon Central Military Road.

After the construction work was completed, Sprague published a list of the best camp sites along the road in the Jacksonville newspapers so that the wagon masters could find the best water and grass along the way.

In February 1866, Major General Frederick Steele arrived at Fort Vancouver to take command of the Military Department of the Columbia.

As soon as the weather improved he ordered the dispersed infantry units, except Captain Sprague's Company I, to report to Fort Vancouver where the volunteers were mustered out of service.

On 19 July 1867, Captain Sprague, First Lieutenant Harrison B. Oatman, and the men of Company I were the last members of the 1st Oregon Volunteer Infantry Regiment to be mustered out of the Army.