The U.S. Army's important history in the Great Land began at the very moment Alaska became American soil on October 18, 1867. Elements of the 9th Infantry were on hand as the Russian Golden Eagle was lowered and the Stars and Stripes were raised in Sitka, which then became headquarters for the Alaska Military District.

Charged with maintaining law and order in the new territory, Soldiers helped quell uprisings and built new forts at Wrangell, St. Paul Canal, Kodiak Island, and on the Kenai Peninsula. They also enforced regulations regarding the killing of fur seals, whose population had been severely depleted during the Russian reign.

The Army relinquished control of Alaska to the U.S. Treasury Department in 1877, but did not entirely leave the territory. The Signal Corps operated weather stations, and a number of officers led small geographic explorations to learn more about the territory. These expeditions into various parts of Alaska continued through the turn of the 20th Century, as mapmaking and road and bridge building expanded the frontier. The Klondike Gold Rush in Yukon Territory, Canada, and later gold rushes in Alaska helped that expansion, as thousands of people poured into Alaska.

Although the Royal Canadian Mounted Police maintained law and order in the Yukon during the Gold Rush, the U.S. government, after sending Captain Patrick H. Ray and First Lieutenant Wilds P. Richardson to study the situation, did not deem it necessary to send the Army into Alaska as peacekeepers. As more and more people came into Alaska and northwestern Canada, the need for better communications with the lower 48 states became critical. The Washington-Alaska Military Cable and Telegraph System (WAMCATS) connected all the forts in the territory with Seattle. By 1903, the line stretched from Seattle to southeastern Alaska, Valdez, the interior, and Nome. The project fell under the direction of Brigadier General Adolphus W. Greely. Lieutenant William "Billy" Mitchell, another officer who would later achieve military fame, also worked on the four-year project.

While Greely and his men struggled to complete the WAMCATS project, Richardson, on his third tour of duty in Alaska, headed the Alaska Road Commission, building garrisons and trails in south-central Alaska. The Army in Alaska saw a decline in activity from 1908 to 1939, with a brief surge during World War I. Work continued building roads and bridges and improving trails during this period.

Military construction in Alaska accelerated in 1940 as the world prepared for another great war. Ladd Field, near Fairbanks, was built as a cold-weather test station and Fort Richardson, named for Wilds P. Richardson, was built near Anchorage. Colonel Simon B. Buckner assumed command of the Alaska Defense Force in 1940, achieving the rank of Major General during his following three-year tenure in what evolved into the Alaska Department.
Through the Lend-Lease Program, the United States transferred nearly 8,000 aircraft to the Soviet Union at Ladd Field, which later became Fort Wainwright. The aircraft were flown from Great Falls, Montana, to Ladd Field by American crews. Russian crews then flew the planes to Siberia and on to the Russian Front. The pilots leaving Great Falls followed a series of small airfields that became known as the Northwest Staging Route. One of those airfields, Big Delta Airfield, later became Fort Greely, providing ample acreage large scale training exercises, northern warfare training and extreme cold weather testing.

Following the Japanese attack on Pearl Harbor in 1941, Army and Navy engineers began building airstrips in the Aleutian Islands to defend against possible Japanese attacks. U.S. Army units also built an initial pioneer road in 1942 for the Alaska-Canada (ALCAN) Highway in less than eight months. In 1943, civilian contractors followed and constructed a more permanent, all-weather highway. The 1,420-mile road was built as an overland supply route to get personnel and equipment to Alaska. The ALCAN Highway complimented military infrastructure that was built throughout Alaska than ensured Allied forces could defend the territory and carry the fight to the enemy, if necessary.

Alaska was the only American soil on which ground fighting occurred during World War II, this following the Japanese bombing of Dutch Harbor and seizure of Attu and Kiska islands in the Aleutian Chain in June, 1942. The successful battle by the U.S. to retake Attu Island in May, 1943, was proportionately one of the most costly amphibious assaults of World War II in the Pacific in terms of American casualties suffered. The Japanese secretly evacuated Kiska in late-July, 1943, several weeks prior to U.S. and Canadian forces seizing the island in mid-August, 1943. At the end of the war, most Army installations throughout the state closed permanently or transferred to other agencies. Postwar emphasis turned to training.

The Alaskan Command (ALCOM) was created in January, 1947. As the first Unified Command under the Department of Defense, ALCOM was headquartered at Elmendorf Air Force Base near Anchorage where it controlled all military forces in Alaska.

The Alaskan Department changed its name again in 1947. The new name for the headquarters for all Army personnel in Alaska became U.S. Army Alaska, or USARAL. Military missions assigned to USARAL included ground and air defense of Alaska, with priority to the Anchorage and Fairbanks areas; development of cold-weather and mountain-warfare doctrines; conducting a cold-weather and mountain school at Fort Greely; providing logistical support to Air Force and Navy elements in Alaska; conducting National Guard and U.S. Army Reserve training; supervising Reserve Officer Training Corps activities; and, providing internal security, including plans for recovery from nuclear attack. By 1959, several Nike Hercules missile battalions were activated in the Anchorage and Fairbanks areas which operated under the last unit inactivated in 1979.
USARAL's combat units officially reorganized in July, 1963, into the 172nd Infantry Brigade Mechanized) at Fort Richardson and the 171st Infantry Brigade (Mechanized) at Fort Wainwright. The two brigades were re-designated as Light Infantry Brigades in 1969.

USARAL was discontinued as a major subordinate command on December 31, 1972, and the 172nd Infantry Brigade (Alaska), headquartered at Fort Richardson, assumed command and control, reporting to U.S. Army Forces Command at Fort McPherson, Georgia. The 171st Infantry Brigade was inactivated in 1973 leaving the reorganized 172nd Infantry Brigade (Separate) as the principal combat formation, split-stationed at both Fort Richardson and Fort Wainwright
The 6th Infantry Division (Light), headquartered at Fort Richardson, was activated in 1986, replacing 172nd Infantry Brigade (Separate). The 6th ID (L) Division headquarters moved to Fort Wainwright in 1990. The 6th 1D (L) maintained an Arctic focus in its unit training and was actively involved in training exercises in Japan and Thailand, at the Joint Readiness Training Center in Arkansas and Louisiana, and throughout Alaska until its inactivation in July 1994. At that time, Army forces in Alaska reorganized under the command of U.S. Army Alaska (USARAK), headquartered at Fort Richardson, with the 172nd Infantry Brigade as the principal combat formation, split-stationed at both Fort Richardson and Fort Wainwright.

The Army underwent a major transformation in the early 2000's that witnessed a significant expansion of forces in Alaska, to include activation of two Brigade Combat Teams and numerous supporting organizations. The Army worked closely with the U.S. Air Force to incorporate Fort Richardson into a Joint Base in 2010, expanded infrastructure at Fort Wainwright, and improved ranges operated within the Joint Pacific-Alaska Range Complex, especially in central Alaska in and around Eielson Air Force Base and Fort Greely.

Today, USARAK is headquartered at Joint Base Elmendorf-Richardson, aligned as a major subordinate command U.S. Army Pacific (USARPAC). USARAK provides trained and ready forces in support of worldwide unified land operations; supports theater engagement in the Pacific/Arctic and military operations in the Alaska Joint Operations Area, in order to contribute to a stable and secure operational environment.

Alaska is now home to two Infantry Brigade Combat Teams, an Aviation Task Force, enabling Echelon Above Brigade units, and Reserve Component units.

The 1st Stryker Brigade Combat Team, 25th Infantry Division is headquartered at Fort Wainwright, near Fairbanks, along with USARAK Aviation Task Force; Northern Warfare Training Center (NWTC); and, U.S. Army Garrison Fort Wainwright.

In addition to the USARAK Headquarters, 4th Brigade Combat Team (Airborne), 25th Infantry Division, SFC Christopher R. Brevard Noncommissioned Officer's Academy, and selected units of the 17th Combat Support Sustainment Battalion are stationed at Joint Base Elmendorf-Richardson.

Other Army-affiliated tenant organizations stationed in Alaska include the DoD Missile Defense Agency (Fort Greely); USA Medical Department Activity-Alaska; USA Dental Activity-Alaska; USA Veterinary Command-Alaska; 59th Signal Battalion; Cold Region Test Center (CRTC), Cold Region Research and Engineering Laboratory (CRREL), USA Research Development and Engineering Command (RDECOM); USA Corps of Engineers, Pacific Ocean Division; 404th Army Field Support Battalion--Alaska; and, supporting elements from Army Material Command. Reserve Component units located throughout the state include Army National Guard Missile Defense, Infantry, and Aviation formations, an Army Reserve Heavy Engineer Company, and an Army Reserve hospital.