- I Corps (ACW)
I Corps (First Corps) was the designation of three different
corps -sized units in theUnion Army during theAmerican Civil War . The units served in the following armies:*
Army of the Ohio /Army of the Cumberland ,Alexander M. McCook ,September 29 ,1862 –November 5 ,1862
*Army of the Mississippi ,George W. Morgan ,January 4 ,1863 –January 12 ,1863
*Army of the Potomac andArmy of Virginia (see below)The first two were units of very limited life; the third was one of the most distinguished and veteran corps in the entire Union Army, commanded by very distinguished officers.
History
The I Corps was activated
March 13 ,1862 , when PresidentAbraham Lincoln ordered the creation of a four-corps army, then under the command of Major GeneralGeorge B. McClellan . The first commander of this corps wasMajor General Irvin McDowell and it contained three divisions. It was held in defense of Washington while the rest of theArmy of the Potomac advanced to thePeninsula Campaign .It was then consolidated into the
Army of Virginia under Major General John Pope, and fought in theSecond Battle of Bull Run , as the Third Corps,Army of Virginia . Afterwards, its name was restored. It rejoined the Army of the Potomac and crossed thePotomac River intoMaryland to fight in theBattle of Antietam , under Major GeneralJoseph Hooker . There, the division ofPennsylvania Reserves , underBrigadier General George G. Meade , took heavy casualties through its hard fighting, and was withdrawn to replenish.The corps moved southward to fight General
Robert E. Lee 's army at theBattle of Fredericksburg , commanded by Major GeneralJohn F. Reynolds , arguably the best Union corps commander in the Eastern Theater. He superbly led the corps through this battle, then through theBattle of Chancellorsville , where the I Corps was left 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 GeneralAbner Doubleday . Although putting up a ferocious fight, the I Corps was overwhelmed by the Confederate Third Corps (A.P. Hill ) andRobert E. Rodes 's division ofRichard S. Ewell 's Second Corps. It was forced to retreat through the town of Gettysburg, taking up defensive positions onCemetery Hill . The next day (July 2 ,1863 ), the command was given to Major General John Newton, a division commander from the VI Corps. This was a controversial move that deeply offended the more senior Doubleday. Newton led it through the remainder of the battle, including the defense againstPickett's Charge , and through theMine Run Campaign that fall.On
March 24 ,1864 , the Civil War career of the I Corps came to an end as it was disbanded and its depleted units were reorganized into two divisions, which were transferred into the V Corps of the Army of the Potomac.Command history
* As III Corps,Army of Virginia References
*Eicher, John H., & Eicher, David J.: "Civil War High Commands", Stanford University Press, 2001, ISBN 0-8047-3641-3
*Fox, William F.: "Regimental Losses in the American Civil War", Albany Publishing, 1889 ( [http://www.civilwarhome.com/1stcorps.htm online text of I Corps section] )
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