Crater Union order of battle

The following Union Army units and commanders fought in the Battle of the Crater (July 30, 1864) of the American Civil War. The Confederate order of battle is listed separately.
Union Forces.
General in Chief.
LTG Ulysses S. Grant, commander in chief
Army of the Potomac.
MG George Meade
Provost Guard:
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BG Marsena R. Patrick
Engineer Brigade:
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BG Henry W. Benham
Signal Corps: Cpt Benjamin F. Fisher
Guards and Orderlies:
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IX Corps.
MG Ambrose Burnside
Provost Guard:
Army of the James.
MG Benjamin F. Butler
Siege Artillery: Col Henry L. Abbot
XVIII Corps.
MG Edward Ord