<P> When Burnside took over command of the army from McClellan in the fall, he formed the army into four Grand Divisions . The Right Grand Division was commanded by Edwin Sumner and comprised the II and V Corps, the Center Grand Division, commanded by Joe Hooker, comprised the IX and III Corps, and the Left Grand Division, commanded by William Franklin, comprised the VI and I Corps . In addition, the Reserve Grand Division, commanded by Franz Sigel, comprised the XI and XII Corps . </P> <P> At Fredericksburg, the I Corps was commanded by John F. Reynolds, the II Corps by Darius Couch, the III Corps by George Stoneman, the V Corps by Daniel Butterfield, the VI Corps by William F. Smith, and the IX Corps by Orlando Willcox . The XI Corps was commanded by Franz Sigel and the XII Corps by Henry Slocum, however neither corps was present at Fredericksburg, the former not arriving until after the battle was over, and the latter was stationed at Harper's Ferry . </P> <P> Following Fredericksburg, Burnside was removed from command of the army and replaced by Joe Hooker . Hooker immediately abolished the Grand Divisions and also for the first time organized the cavalry into a proper corps led by George Stoneman instead of having them ineffectually scattered among infantry divisions . Burnside and his old IX Corps departed out to a command in the Western Theater . The I, II, and XII Corps retained the same commanders they had had during the Fredericksburg campaign, but the other corps got new commanders once again . Daniel Butterfield was chosen by Hooker as his new chief of staff and command of the V Corps went to George Meade . Daniel Sickles received command of the III Corps and Oliver Howard the XI Corps after Franz Sigel had resigned, refusing to serve under Hooker, his junior in rank . William Franklin also left the army for the same reason . Edwin Sumner, who was in his 60s and exhausted from campaigning, departed as well and died a few months later . William F. Smith resigned from command of the VI Corps, which was taken over by John Sedgwick . The I and V Corps were not significantly engaged during the Chancellorsville campaign . </P> <P> During the Gettysburg Campaign, the army's existing organization was largely retained, but a number of brigades composed of short - term nine month regiments departed as their enlistment terms expired . Darius Couch resigned from command of the II Corps after Chancellorsville, the corps going to Winfield Hancock . The Pennsylvania Reserves Division, having spent several months in Washington D.C. resting and refitting from the 1862 campaigns, returned to the army, but was added to the V Corps rather than rejoining the I Corps . George Stoneman had been removed from command of the cavalry corps by Hooker after a poor performance during the Chancellorsville campaign and replaced by Alfred Pleasanton . </P>

Who of the following had command of the army of the potomac