US I Corps

I Corps (United States)

The I Corps (First Corps) aka ("eye core"), nicknamed America's Corps, is a corps of the United States Army with headquarters in Fort Lewis, Washington. The I Corps serves under the United States Army Pacific (USARPAC). The current I Corps is a different organization from the I Corps of the Union Army during the American Civil War.


Civil War

In the American Civil War, the I Corps was one of the most accomplished and veteran corps in the Union Army, commanded by distinguished officers. It was created in March 1862, when President Abraham Lincoln ordered the creation of a four-corps army under Major General George B. McClellan. The first commander of the I Corps was Major General Irvin McDowell. The three divisions of the I Corps were held in defense of Washington, D.C., while the rest of the Army of the Potomac advanced to the Peninsula Campaign.

The corps was consolidated in the Army of Virginia under Major General John Pope, and fought in the Second Battle of Bull Run, as the Third Corps, Army of Virginia. Afterwards, its designation as I Corps was restored. Iit rejoined the Army of the Potomac and crossed the Potomac River into Maryland to fight in the Battle of Antietam, under Major General Joseph Hooker. There, the division of Pennsylvania Reserves, under Brigadier General George G. Meade, took heavy casualties through its hard fighting, and was withdrawn to replenish.

The command of the Army of the Potomac then changed to Major General Ambrose E. Burnside, and they moved southward to fight General Robert E. Lee's army at the Battle of Fredericksburg, where the corps was commanded by Major General John F. Reynolds, arguably the best Union corps commander in the Eastern Theater. He superbly led the corps through this battle, then through the Battle of Chancellorsville, with the army being led by General Hooker, who left the I Corps in reserve.

In its last major battle, the Battle of Gettysburg, General Reynolds was killed just as the first troops arrived on the field, and command was inherited by Major General Abner Doubleday. Although putting up a ferocious fight, the I Corps was overwhelmed by the Confederate Third Corps (A.P. Hill) and forced to retreat through the town of Gettysburg, taking up defensive positions on Cemetery Hill. The next day (July 2, 1863), the command was given to Major General John Newton, a division commander from the VI Corps, who led it through this battle, including the defense against Pickett's Charge, and through the Mine Run Campaign that fall. Afterwards, the I Corps was disbanded and its units were reorganized and absorbed into the rest of the army. The Civil War career of the I Corps was ended.

Spanish-American War

The corps was reactivated in 1898 for the Spanish-American War, under the leadership of Major General John R. Brooke, and elements landed on July 31, 1898, to take part in the Puerto Rico Campaign. It advanced to Guayama, where it fought a battle on August 5, but the armistice was signed before they could partake in a slated major attack. Both the I Corps from the 19th Century are unrelated to the current I Corps even though they carry the same name.

World War I

Following the American declaration of war on the country of Germany, on April 6, 1917, the I Corps was organized and activated on January 15–20, 1918, in the National Army in Neufchâteau, France, as Headquarters & Headquarters Company, I Army Corps. Assisted by the French XXXII Corps, the headquarters was organized and trained; on January 20, Major General Hunter Liggett took command.

In February, the corps consisted of the 1st, 2d, 26th, 32d, 41st, and 42d Infantry Divisions. From February to July, 1918, the German Army launched four major offensives, attempting to secure victory before the full American force could be brought to bear. The final offensive, started in July 1918, was an attempt to cross the Marne, in the area of Chateau-Thierry, but the American lines (including I Corps) held, and the offensive was fought back.

Joseph T. Dickman, who had commanded 3rd Infantry Division during their famous stand at the Second Battle of the Marne, took command in October 1918, leading the unit during the Meuse-Argonne Offensive.

Thereafter, the I Corps, along with other U.S. and Allied units, moved forward, breaking the German will to fight, until the armistice, signed on November 11, 1918.

The I Corps shoulder sleeve insignia was approved by the Adjutant General, American Expeditionary Forces on December 3, 1918.

The I Corps continued to train in France, until it was demobilized on March 25, 1919. I Army Corps was immediately returned to the inactivated list.


1st, 2d, 3d, 4th, 5th, 6th, 26th, 28th, 32d, 35th, 36th, 41st, 43d, 77th, 78th, 80th, 82d, 90th, 91st, and 92d Divisions (United States).

62d, 167th, and 5th Cavalry Divisions (French).

Interwar period

World War II

  • The original Distinctive Unit Insignia for I Corps was approved on June 8, 1942.
  • Redesignated August 19, 1942 as Headquarters, I Corps, and moved to Australia.
  • Deployed to the Pacific Theater September 11, 1942.
  • Reconstituted June 27, 1944. In the Regular Army as Headquarters, I Corps; concurrently consolidated with Headquarters, I Corps (active) (see Australian information), and Consolidated unit designated as Headquarters, I Corps.

During World War II, the corps fought in the South West Pacific Area. Its initial operations were in Papua, reinforcing Australian forces, which had turned back Japanese attacks along the Kokoda Track. The Allied forces then took the offensive, against the Japanese beachheads at Buna and Gona.

Thereafter, I Corps engaged in the western part of Operation Cartwheel, the encircling and neutralization of the Japanese base at Rabaul in New Britain. After this operation was completed, I Corps took part in prolonged Allied mopping-up operations along the northern shores of New Guinea.

In by far the largest series of operations in the theater during the war, I Corps took part in the invasion of Luzon. It was still engaged on mopping up operations there at the end of the war.

After the end of hostilities, I Corps was assigned to Occupation Force Duty in Japan.

Headquarters & Headquarters Company, I Corps was demobilized on March 28, 1950, in Japan, and returned to the Inactive list.

Modern period

  • HHC, I Corps was reactivated August 2, 1950, at Fort Bragg, North Carolina, and was assigned to take control of the UN Forces in the Korean War.
  • Reassigned to Fort Jay, New York, as its Home Post on May 21, 1951, concurrent with the reactivation of XVIII Airborne Corps at Fort Bragg.
  • Reorganized and redesignated December 1, 1967, as Headquarters and Headquarters Company, I Corps.
  • A second Distinctive Unit Insignia was authorized on May 21, 1970.
  • A third DUI design was approved on September 14, 1982 and cancelled on October 31, 1988.
  • The current Distinctive Unit Insignia was approved on October 31, 1988.
  • I Corps (Forward) Served in Mosul, Iraq, from January 2004 - January 2005. Led by Brigadier General Carter F. Ham based from Fort Lewis.

Current Structure

I Corps (Fort Lewis, WA)

* 17th Fires Brigade (Fort Lewis, WA)
* 42nd Military Police Brigade (Fort Lewis, WA)
* 62nd Medical Brigade (Fort Lewis, WA)
* 201st Battlefield Surveillance Brigade (Fort Lewis, WA)
* 555th Engineer Brigade (Fort Lewis, WA)
* 10th Sustainment Command, (Fort Lewis, WA)
** 593rd Sustainment Brigade (Fort Lewis, WA)


I Corps

Organized 1918-01-15 - 1918-01-20 in the Regular Army in France as Headquarters, I Army Corps

Demobilized 1919-03-25 in France

Reconstituted 1944-06-27 in the Regular Army as Headquarters, I Corps; concurrently consolidated with Headquarters, I Corps (active) (See below), and consolidated unit designated as Headquarters, I Corps

Inactivated 1950-03-28 in Japan

Activated 1950-08-02 at Fort Bragg, North Carolina

Reorganized and redesignated 1967-12-01 as Headquarters and Headquarters Company, I Corps

I Corps (Active)

Constituted 1927-08-15 in the Regular Army as Headquarters, XX Corps

Redesignated 1927-10-13 as Headquarters, I Corps

Activated 1940-11-01 at Columbia, South Carolina

Redesignated 1941-01-01 as Headquarters, I Army Corps

Redesignated 1942-08-19 as Headquarters, I Corps


Campaign participation credits


  1. Presidential Unit Citation (Army) for Papua
  2. Army Superior Unit Award - for 1999-2000
  3. Philippine Presidential Unit Citation for October 17, 1944 TO July 4, 1945
  4. Republic of Korea Presidential Unit Citation for Korea 1950-1953
  5. Meritorious Unit Citation for Iraq 2004-2005


  • Seon, SSG Cornelius, NYARNG (Retired), US Army Center for Military History; Lineage and Honors Information as of 7 September 2001.

External links & Further Reading

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