Blenker had led a German brigade at First Bull Run, although it was held in reserve and saw no major fighting, and afterward became a division commander in the new Army of the Potomac.

Gen Carl Schurz wrote to President Lincoln that the German regiments suffered from hunger, lack of tents and shoes, and could barely fight.

This order of President Lincoln was included in the one constituting John Pope's Army of Virginia, which was formed from the three commands of Frémont, Nathaniel P. Banks, and Irvin McDowell.

In early August, Louis Blenker stepped down from command due to the lingering effects of an injury sustained during the spring; he died in October 1863.

Sigel was in command at the Second Battle of Bull Run, where the corps was in the thick of the fighting, losing 295 killed, 1,361 wounded, and 431 missing; total, 2,087.

On the second day, it was in the middle of the desperate fighting against James Longstreet's Confederates on Chinn Ridge, where Sigel and Schneck were wounded and Col. John Koltes, one of the brigade commanders, was killed.

The corps had suffered severely at Second Bull Run and came close to being routed from the field, so it was left behind in Washington D.C. during the Maryland Campaign to rest and refit.

Replacing him was Maj. Gen. Oliver Otis Howard, who had lately been complaining that he deserved a corps command since General Daniel Sickles, his junior in rank, had gotten one.

Howard quickly established a poor relationship with the troops due to his intense religious fervor, which especially alienated the anti-clerical Germans, and for bringing in two new, unpopular generals, Francis Barlow and Charles Devens.

Although General Howard had been warned of Confederate movement across his front, he took no steps to prepare his command against Jackson's attack; only two inoperative artillery pieces were pointed at the Wilderness.

Some of the brigades changed front to meet the attack, barely resisting, and were pushed back, hardly slowing the enemy down, but most of the corps fled to the east, running down the Orange Turnpike past the crossroads at Chancellorsville.

At Gettysburg, the corps was still under the command of Howard; the divisions were under Generals Francis C. Barlow, Steinwehr, and Schurz, and contained 26 regiments of infantry and 5 batteries of artillery.

Returning to Virginia after Gettysburg, on August 7, the 1st Division (Alexander Schimmelfennig's and later George Henry Gordon's) was permanently detached, having been ordered to Charleston Harbor.

During the following month, on October 29, Howard's two divisions were ordered to support the XII Corps at the Battle of Wauhatchie, opening the supply lines to the besieged city of Chattanooga.

Arriving there, Col. Orland Smith's Brigade of von Steinwehr's Division charged up a steep hill in the face of the enemy, receiving but not returning the fire, and drove James Longstreet's veterans out of their entrenchments, using the bayonet alone.

After this battle, it was ordered to East Tennessee for the relief of Knoxville, a campaign whose hardships and privations exceeded anything within the previous experience of the command.