The Union infantry force at Gettysburg comprised seven corps.  Identify them, and name the commander of each at the start of the battle.

Answer: 

I Corps:    Major Gen. John F.  Reynolds.

II Corps:   Major Gen. Winfield S. Hancock.

III Corps:   Major Gen. Daniel E. Sickles.

V Corps:   Major Gen. George Sykes

VI Corps:  Major Gen. John Sedgwick

XI Corps:   Major Gen. Oliver O. Howard

XII Corps:  Major Gen. Henry Slocum

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( Source: NPS  ) 01-01-09