The First Corps, Army of Northern Virginia (or Longstreet's Corps) was a military unit fighting for the Confederate States of America in the American Civil War. It was formed in early 1861 and served until the spring of 1865, mostly in the Eastern Theater. The corps was commanded by James Longstreet for most of its existence. In part or as a whole, the corps fought in nearly all of the major battles in the Eastern Theater, such as Fredericksburg, Gettysburg, The Wilderness, Cold Harbor, and the Siege of Petersburg. The corps also fought in Tennessee and performed important forage service in Suffolk, Virginia. It was disbanded shortly following Gen. Robert E. Lee's surrender to Union forces on April 9, 1865. Origins On June 1, 1862, Robert E. Lee took command of the Army of the Potomac following Johnston's wounding during Battle of Seven Pines, and shortly afterwards this army would be known as the Army of Northern Virginia. Lee re-organized the army as two "wings" (corps were not legally allowed by the Confederate Congress until September 18), with Lt. Gen. James Longstreet in charge of the Right Wing and Lt. Gen.Thomas J. "Stonewall" Jackson in charge of the Left Wing. With the authorization of corps later that year, the Right Wing was redesignated as the First Corps. At this time, Longstreet's corps contained twenty-one brigades organized into five divisions under major generals Lafayette McLaws, Richard H. Anderson, George E. Pickett, and John B. Hood, and Brigadier General Robert Ransom, Jr. 1862 Fredericksburg Note: see Fredericksburg order of battle for the command structure of the Army of Northern Virginia at this time. The Battle of Fredericksburg was fought in and around Fredericksburg, Virginia, starting on December 11 and concluding December 15, 1862, between Lee's Army of Northern Virginia and the Federal Army of the Potomac, now commanded by Maj. Gen. Ambrose E. Burnside. The First Corps started reaching Marye's Heights on November 18 and deployed there to contest a possible pontoon crossing of the Union army at Fredericksburg, with the Second Corps following quickly once Lee was more certain of Burnside's intentions. Until Lee was convinced, the First Corps did not deeply entrench until a couple of weeks before the actions on December 12. After Jackson's arrival on December 2, Longstreet started entrenching along his portion of the line, with Anderson's division near Banks Ford on the Rappahannock and the remaining