The regiment was organized and mustered by 8 May at Camp McKinley on the racetrack grounds at Irving Park in Portland,^[4][5] and named the 2nd as the 1st had been organized in 1864 to guard trade routes and escort immigrant wagon trains.^[6] After a few days training under Colonel Owen Summers, it departed for the Presidio of San Francisco.^[7] On 25 May, the regiment embarked at San Francisco en route for the Philippines.^[2]

On 21 June, the 2nd Oregon participated in the surrender of Guam.^[2] The 2nd Oregon next landed at the Philippines, the first U.S. Army unit to do so.^[2] It was also the first unit to enter the Walled City of Manila, and took part in the surrender of the Spanish army in Manila on 13 August. Beginning on 16 August, the regiment served guard duty in Manila