World War I Following the
American declaration of war on Germany, on 6 April 1917, the I Corps was organized and activated on 15–20 January 1918, in the
National Army in
Neufchâteau, France, the first of several corps-sized formations intended to command
divisions of the
American Expeditionary Forces in Europe during World War I. Assisted by the
French XXXII Corps, the headquarters was organized and trained; on 20 January, Major General
Hunter Liggett took command. In February, the corps consisted of the
1st,
2nd,
26th,
32nd,
41st, and
42nd Infantry Divisions. From February to July, 1918, the
German Army launched four major offensives, attempting to secure victory before the full American forces could be mobilized. The final offensive, started in July 1918, was an attempt to cross the
Marne, in the area of
Château-Thierry, but the I Corps and other formations on the American lines held, and the attack was rebuffed. The I Corps continued to train in France, until it was demobilized on 25 March 1919.
World War II New Guinea Campaign On 6 July 1942
Lieutenant General Robert L. Eichelberger took command of the corps which he would lead through the majority of its service in the war. In the summer of 1942 the corps was ordered to Australia, closing into the area at
Rockhampton on 17 October 1942. This move was to be part of a larger overall offensive in the south Pacific region. The corps at this time comprised the 41st and 32nd Divisions, engaged in the defense of
British New Guinea, the beginning of the
New Guinea campaign. Though the Japanese advanced rapidly at first, a number of factors slowed their progress against the Allied forces. Stubborn resistance from two Australian brigades bought time for I Corps reinforcements to arrive while the terrain proved more difficult than the Japanese had anticipated. Supplies, which were already insufficient for the Japanese forces, were shortened even more as Japan's high command diverted them to the
Guadalcanal campaign. The Japanese attack stalled, and once the threat of a Japanese invasion of Australia was abated, the I Corps launched an offensive to push back the Japanese. With the 32nd Division and the
163rd Infantry Regiment of the 41st Division, the offensive was launched across the
Owen Stanley Mountains of New Guinea. Despite being surrounded, trapped, and outnumbered, the Japanese forces continued to fight until they were completely wiped out by Allied forces.
Buna, on the north coast of the island, fell on 22 January 1943. The campaign was the first major Allied victory against the Japanese Army, and the I Corps received the
Distinguished Unit Citation. This victory marked the turn of the tide in the ground war against Japan. The Task Force established itself ashore after a successful amphibious assault on 19 April 1944. It then began an offensive in that area to remove Japanese forces, before establishing air bases there. As a part of the Sixth Army with an overall force of 175,000 men, the American forces faced over 260,000 Japanese in Luzon. In a sustained drive of thirty-four days which covered over 100 miles, the I Corps crossed central Luzon and thus separated the Japanese forces in the north from those in southern Luzon, destroying Japanese armored units along the way. Additional landings at
Samar and
Palawan were conducted in February, reducing the pressure on the forces of the I Corps. Following this accomplishment, the corps turned northward and began the systematic reduction of the enemy positions on the approach to the
Cagayan Valley. The breakthrough into the valley was followed by a swift exploitation that took the corps to the north coast. This advance covered two hundred miles in little over 100 days; eliminating effective enemy resistance in northern Luzon. The intense fighting that ensued cost 8,000 killed and 30,000 wounded in the Sixth Army, compared to 190,000 dead for Japan. With the defeat of the Japanese at each of these places, the US forces had locations from which to launch attacks into mainland Japan. Allied forces then began preparing for the invasion of mainland Japan,
Operation Downfall. The I Corps was assigned as one of four Corps under the command of the Sixth Army, with a strength of 14 divisions. The I Corps was to lead the assault on
Miyazaki, in southern
Kyūshū, with the 25th, 33rd, and 41st Infantry Divisions. Opposing them would be the Japanese 57th Army, with the 154th, 156th, and 212th Japanese Infantry Divisions. But the assault was not required. Japan surrendered following the use of
nuclear weapons on Hiroshima and Nagasaki. During World War II, the
6th,
8th,
9th,
24th,
25th,
30th (during training in U.S. only?),
32nd,
33rd,
37th,
41st,
43rd,
77th and
98th Infantry Divisions were assigned to the I Corps at one time or another, along with the
2nd Marine Division,
7th Australian Division, and elements of the
11th Airborne Division. The next few years were a period during which the terms of the surrender were supervised and enforced; Japanese military installations and material were seized, troops were disarmed and discharged, and weapons of warfare disposed of. The duties of the occupation force included conversion of industry, repatriation of foreign nationals, and supervision of the complex features of all phases of Japanese government, economics, education, and industry. By 1948, as the purely occupational mission was accomplished, troops of the corps focused more military training and field exercises designed to prepare them for combat. Its force was eventually downsized to the
24th Infantry Division on Kyūshū and
25th Infantry Division on mid-Honshū. The US Army continued a slow and steady process of post-war drawdown and demobilization on its own, and on 28 March 1950, the corps was formally inactivated in Japan, and its command consolidated with other units. It took command of the
1st Cavalry Division, 24th Infantry Division and the ROK
1st Infantry Division, along with the
27th British Commonwealth Brigade, defending the
Naktong River area against attacking North Korean units. Amphibious
landings at Inchon by the
X Corps hit
Korean People's Army (KPA) forces from behind, allowing the I Corps to
breakout from the Pusan perimeter starting on 16 September. Four days later I Corps troops
began a general offensive northward against crumbling KPA opposition to establish contact with forces of the
7th Infantry Division driving southward from the beachhead. Major elements of the KPA were destroyed and cut off in this aggressive penetration; the link-up was effected south of
Suwon on 26 September. In the wake of the retreat, the disorganized Eighth Army regrouped and re-formed in late December. The I Corps relinquished command of the 1st Cavalry Division, the 24th Infantry Division and the 27th British Brigade, taking command of the
3rd Infantry Division and the
25th Infantry Division in their place. On 1 January 1951, 500,000 PVA troops attacked the Eighth Army's line at the Imjin River, forcing them back and allowing the PVA to
capture Seoul. Following the establishment of defenses south of the capital city, General
Matthew B. Ridgway ordered the I,
IX and X Corps to conduct a general counteroffensive against the PVA/KPA,
Operation Thunderbolt. Between February and March, the corps participated in
Operation Killer, pushing PVA forces north of the
Han River. This operation was quickly followed up with
Operation Ripper, which retook Seoul in March. After this
Operation Rugged and
Operation Dauntless in April saw Eighth Army forces advance north of the 38th Parallel and reestablish themselves along the Kansas Line and Utah Line, respectively. Though the 24th and 25th Infantry Divisions were able to hold their ground against the PVA 9th Army Corps, the ROK
6th Infantry Division, to the east,
was destroyed by the PVA 13th Army Corps, which penetrated the line and threatened to encircle the American divisions. The
1st Marine Division and the 27th British Commonwealth Brigade were able to drive the PVA 13th Army Corps back while the 24th and 25th Divisions withdrew on 25 April.
Stalemate In September, the UN Forces launched another
counteroffensive with the 24th Infantry Division at the center of the line, west of the
Hwachon Reservoir. Flanked by the ROK 2nd and 6th Divisions, the 24th advanced past Kumwha, engaging the PVA
20th and
27th Armies. In late 1951, the 1st Cavalry Division, depleted after having suffered 16,000 casualties so far in the conflict, was relegated to the Far East reserve to rebuild. It was replaced by the
45th Infantry Division of the
Oklahoma Army National Guard, which was newly arrived in the theater. In 1988, the
distinctive unit insignia was approved for the corps. This was the fourth design held by the corps, with previous versions being approved then retracted in 1942, 1970, and 1982.
War on terrorism With the events of 11 September 2001, the I Corps began providing support for Army units deploying in support of the
war on terrorism. Its assets were active in providing
combat support and
combat service support missions, including
Operation Enduring Freedom in Afghanistan,
Operation Iraqi Freedom in Iraq and the domestic
Operation Noble Eagle. The I Corps filled the role of
Multi-National Corps - Iraq at
Al-Faw Palace. In January 2010, Multi-National Corps - Iraq integrated with
Multi-National Forces - Iraq (MNF-I) and
Multi-National Security Transition Command – Iraq (MNSTC-I) to form
United States Forces - Iraq (USF-I). Over its one-year deployment, the corps oversaw the responsible drawdown of major components of US Forces in Iraq. I Corps returned from Iraq in March 2010 following their RIP/TOA with the III Corps. The I Corps headquarters deployed to Afghanistan to serve as the headquarters of the
International Security Assistance Force Joint Command (IJC) for a period of one year. The commander of the I Corps, Lieutenant General
Curtis Scaparrotti, served concurrently as the commander of the International Security Assistance Force Joint Command and Deputy Commander, U.S. Forces – Afghanistan from 11 July 2011 to 11 July 2012.
Asia-Pacific shift The I Corps shifted its mission to the
Asia-Pacific region in mid-2012. The I Corps Commander Lt. Gen. Robert Brown announced this
Pacific Rim rebalance during his Change-of-Command Ceremony at
Joint Base Lewis-McChord. In late 2011, President
Barack Obama and Secretary of Defense
Leon Panetta signaled the Asia-Pacific pivot and made several trips to the region. The
Pacific Rim Rebalance will involve several combined and joint military exercises in Japan, South Korea,
Thailand,
Philippines, and Australia. Part of the I Corps' objectives for these exercises will be Joint
Task Force certification in support of
United States Pacific Command missions. As part of the Army Transformation Initiative in late 2025, the Army consolidated oversight of Indo-Pacific forces. This included the reassignment of the 4th Infantry Division to I Corps to synchronize logistics and modernization efforts west of the International Date Line. == Organization ==