text: D.H. Hill's division numbered around 7700 men, having numbered close to 10,000 before the heavy losses at Seven Pines. They were reinforced with Roswell Ripley's brigade, newly arrived from North Carolina, and numbering 2300 men, bringing the total strength of Hill's command to 10,000 men. James Longstreet's division numbered 9050 men on June 25 according to army ordnance chief Edward P. Alexander. It had numbered close to 12,000 men prior to losses at Seven Pines. Benjamin Huger's division numbered approximately 8600 men. William Whiting had around 4000 men in his two brigades. John Magruder's three divisions numbered about 13,000 men.
  Union
  McClellan's Army of the Potomac, with approximately 105,000 men, was organized largely as it had been at Seven Pines.
  II Corps, Brig. Gen. Edwin V. Sumner commanding: divisions of Brig. Gens. Israel B. Richardson and John Sedgwick.
  III Corps, Brig. Gen. Samuel P. Heintzelman commanding: divisions of Brig. Gens. Joseph Hooker and Philip Kearny.
  IV Corps, Brig. Gen. Erasmus D. Keyes commanding: divisions of Brig. Gens. Darius N. Couch and John J. Peck.
  V Corps, Brig. Gen. Fitz John Porter commanding: divisions of Brig. Gens. George W. Morell, George Sykes, and George A. McCall.
  VI Corps, Brig. Gen. William B. Franklin commanding: divisions of Brig. Gens. Henry W. Slocum and William F. "Baldy" Smith.
  Reserve forces included the cavalry reserve under Brig. Gen. Philip St. George Cooke (Jeb Stuart's father-in-law) and the supply base at White House Landing under Brig. Gen. Silas Casey.
  Confederate
  Lee's Army of Northern Virginia was larger than the one he inherited from Johnston, and, at about 92,000 men, the largest Confederate army assembled during the war.