On July 27, 1865 the Military Division of the Pacific was created under Major General Henry W. Halleck, replacing the Department of the Pacific, consisting of the Department of the Columbia (replacing the District of Oregon) that now consisted of the state of Oregon and the territories of Washington and Idaho and the expanded Department of California.
The Military District of Alaska, was formed, subordinate to the Department of the Columbia in 1867 following the purchase of Alaska. On March 18, 1868, the Army established the Department of Alaska under the Division of the Pacific. The Department of Alaska was discontinued on July 1, 1870, and Alaska was absorbed again by the Department of the Columbia.
In June 1875, the part of the Territory of Idaho that lay east of the extension of the western boundary of Utah, and including Fort Hall, was detached from the Department of Columbia and added to the Department of the Platte.
When the Military Division of the Pacific was discontinued on July 3, 1891. Each of its three subordinate departments including the Department of the Columbia, then reported directly to the War Department.
Commanders of the Military Department of Columbia
- Brigadier General George Wright, July 27, 1865 – July 30, 1865
- Colonel George Byron Currey, July 27, 1865 – November 20, 1865
- Lieutenant Colonel John M. Drake, November 20, 1865 – December 22, 1865
- Major General Frederick Steele, December 21, 1865 – November 23, 1867
- Lieutenant Colonel George Crook, November 23, 1867 – August 8, 1870
- Brigadier General Edward Richard Sprigg Canby, August 8, 1870 – January 1873
- Colonel Jefferson Columbus Davis, January 1873 – September 1874
- Brigadier General Oliver Otis Howard, September 1874 – January 1881
- Brigadier General Nelson A. Miles, January 1881 – July 1885
- Brigadier General John Gibbon, July 1885 – April 1891
- Brigadier General August Kautz, April 1891 – January 1892
Posts in the Military Department of Columbia
- Fort Colville, Washington Territory, 1859–1882
- Fort Steilacoom, Washington Territory, 1849–1868
- Fort Dalles, Oregon, 1850–1867
- Fort Vancouver, Washington Territory, 1853–1879
- Fort Yamhill, Oregon, 1856–1866
- Fort Walla Walla, Washington Territory, 1856–1911
- Siletz Blockhouse, Oregon, 1858–1866 
- Post of San Juan, Washington Territory, 1863–1867
- Fort Cape Disappointment, Washington Territory, 1864–1875 
- Fort Canby, 1875–
- Fort Lapwai, Idaho Territory, 1862–1884
- Fort Boise, Idaho Territory, 1863–1912
- Fort Klamath, Oregon, 1863–1890
- Fort at Point Adams, Oregon, 1863–1865 
- Fort Stevens, Oregon, 1865 - 1947
- Camp Alvord, Oregon, 1864–1866 
- Camp Henderson, Oregon, 1864–1866 
- Camp Watson, Oregon, 1864–1869
- Camp Colfax, Oregon, 1865, 1867
- Camp Currey, Oregon, 1865–1866 
- Camp Lander, Idaho Territory, 1865–1866 
- Camp Logan, Oregon, 1865–1868 
- Camp Lyon, Idaho, 1865–1869 
- Camp Polk, Oregon, 1865–1866 
- Camp Reed, Idaho Territory, 1865–1866 
- Camp on Silvies River, Oregon ? 
- Camp Wright, Oregon 1865–1866 
- Old Camp Warner, Oregon, 1866–1867
- Camp Warner, Oregon, 1867���1874
- A two-story blockhouse built to protect the Siletz Indian Agency. It was a subpost of Fort Hoskins. Originally called Yaquina Bay Blockhouse (1856–1858) located at the mouth of the Yaquina River near South Beach. It was dismantled and floated upriver in 1858. Located at Siletz, Oregon.
- Post at Cape Disappointment 1862–63, was at the north mouth of the Columbia River, Washington Territory, later renamed Fort Cape Disappointment 1864 and Fort Canby in 1875.
- Carey, History of Oregon, pg. 672. Located on the south shore of the mouth of the Columbia River. Later named Fort Stevens.
- Carey, History of Oregon, pg. 671. On Horse Creek in the Alvord Valley, east of the Steen Mountain Range
- Carey, History of Oregon, pg. 671. This camp, named for Oregon's representative in Congress at that time, was established early in 1864, near the mouth of Jordan Creek, 330 miles from Walla Walla, and was the center of operations in Southeastern Oregon for some time afterward.
- Carey, History of Oregon, pg. 671. At the Willow Creek crossing of the Canyon City – Boise Road, south of Baker City.
- Carey, History of Oregon, pg. 671. On Silver Creek.
- Carey, History of Oregon, pg. 671. On the Snake River, at the site of Old Fort Hall in S. Idaho Territory.
- Carey, History of Oregon, pg. 671 East of Canyon City, on the road to Colfax.
- Carey, History of Oregon, pg. 671 In the Jordan Valley, east of the Owyhee River.
- IDAHO STATE HISTORICAL SOCIETY REFERENCE SERIES, CAMP LYON, Number 357 July 16, 1965
- Carey, History of Oregon, pg. 671. On the Deschutes River near the mouth of Crooked River.
- Carey, History of Oregon, pg. 671,674. On the Snake River, near Salmon Falls, in S. Idaho Territory.
- Carey, History of Oregon, pg. 674. Located on the on Silvies River, north of Malheur Lake.
- Carey, History of Oregon, pg. 671. North of Harney Lake. A temporary state militia encampment on the Silvies River, possibly to the south of Burns, Oregon. . Originally Adobe Camp (1865), a 25-yard square sod-walled post, was located here before being replaced after only two weeks.
- Carey, History of Oregon, pg. 671. Located east of Warner Lakes. A Federal camp originally located 20 miles east of Warner (Hart) Lake. It was moved in 1867
- Carey, History of Oregon, pg. 671. Located west of Warner Lakes.