Major battle of the American Civil War
The Battle of Seven Pines, also known as the Battle of Fair Oaks or Fair Oaks Station, took place on May 31 and June 1, 1862, in Henrico County, Virginia as part of the Peninsula Campaign of the American Civil War. 
The Union's Army of the Potomac, commanded by Maj. Gen. George B. McClellan, had moved up the Virginia Peninsula, reaching the outskirts of Richmond, the Confederate capital. On May 31, Confederate General Joseph E. Johnston attempted to overwhelm two Federal corps that appeared isolated south of the Chickahominy River.
The Confederate assaults, although poorly coordinated, succeeded in driving back the IV Corps and inflicting heavy casualties. Reinforcements arrived, and both sides fed more and more troops into the action. Supported by the III Corps and Maj. Gen. John Sedgwick's division of Maj. Gen. Edwin V. Sumner's II Corps (which crossed the rain-swollen river on Grapevine Bridge), the Federal position was finally stabilized.
Gen. Johnston was seriously wounded during the action, and command of the Confederate army devolved temporarily to Maj. Gen. G.W. Smith.
On June 1, the Confederates renewed their assaults against the Federals, who had brought up more reinforcements, but made little headway. Both sides claimed victory.
Although the battle was tactically inconclusive, it was the largest battle in the Eastern Theater up to that time (and second only to Shiloh in terms of casualties thus far, about 11,000 total). Gen. Johnston's injury also had profound influence on the war: it led to the appointment of Robert E. Lee as Confederate commander. The more aggressive Lee initiated the Seven Days Battles, leading to a Union retreat in late June. Seven Pines therefore marked the closest Union forces came to Richmond until near the end of the war.
Background.
Johnston withdrew his 75,000-man army from the Virginia Peninsula as McClellan's army pursued him and approached the Confederate capital of Richmond. Johnston's defensive line began at the James River at Drewry's Bluff, site of the recent Confederate naval victory, and extended counterclockwise so that his center and left were behind the Chickahominy River, a natural barrier in the spring when it turned the land to the east of Richmond into swamps. Johnston's men burned most of the bridges over the Chickahominy and settled into strong defensive positions north and east of the city. McClellan positioned his 105,000-man army to focus on the northeast sector, for two reasons. First, the Pamunkey River, which ran roughly parallel to the Chickahominy, offered a line of communication that could enable McClellan to get around Johnston's left flank. Second, McClellan anticipated the arrival of the I Corps under Maj. Gen. Irwin McDowell, scheduled to march south from Fredericksburg to reinforce his army, and thus needed to protect their avenue of approach.
The Army of the Potomac pushed slowly up the Pamunkey, establishing supply bases at Eltham's Landing, Cumberland Landing, and White House Landing. White House, the plantation of W.H.F. "Rooney" Lee, son of General Robert E. Lee, became McClellan's base of operations. Using the Richmond and York River Railroad, McClellan could bring his heavy siege artillery to the outskirts of Richmond. He moved slowly and deliberately, reacting to faulty intelligence that led him to believe the Confederates outnumbered him significantly. By the end of May, the army had built a few bridges across the Chickahominy and was facing Richmond, straddling the river, with one third of the Army south of the river, two thirds north.
Opposing forces.
Union.
The Union Army of the Potomac of 105,000 men was near the outskirts of Richmond to the northeast, straddling the Chickahominy River. There were three corps north of the river, protecting the Union railroad supply line: the V Corps under Brig. Gen. Fitz John Porter; the VI Corps, under Brig. Gen. William B. Franklin; and the II Corps, under Brig. Gen. Edwin V. Sumner. South of the river were the IV Corps, under Brig. Gen. Erasmus D. Keyes, in a position far forward and close to the Confederate lines; and the III Corps, under Brig. Gen. Samuel P. Heintzelman. At the start of the battle on May 31, McClellan was confined to bed, ill with a flare-up of his chronic malaria.
Confederate.
Johnston had 60,000 men in his Army of Northern Virginia protecting the defensive works of Richmond in eight divisions commanded by Maj. Gen James Longstreet, Maj.
Gen D.H. Hill, Maj. Gen Benjamin Huger, Maj. Gen Gustavus Smith, Maj. Gen A.P. Hill (who had just gotten command of a brand-new division on May 27), Maj. Gen John B. Magruder, Brig. Gen David Rumph Jones, and Maj. Gen Lafayette McLaws. Just prior to the battle, Johnston appointed Longstreet, Smith, and Magruder as wing commanders. Longstreet had the right wing, consisting of his own division, D.H. Hill's, and Huger's. Smith had the left wing, consisting of his division and A.P. Hill's, while Magruder had his division, Jones, and McLaws in the reserve wing. Brig. Gen Richard H. Anderson and Brig. Gen William H.C. Whiting had operational command of Longstreet and Smith's divisions.
Johnston's plan.
Johnston, who had retreated up the Peninsula to the outskirts of Richmond, knew that he could not survive a massive siege and decided to attack McClellan. His original plan was to attack the Union right flank, north of the Chickahominy River, before McDowell's corps, marching south from Fredericksburg, could arrive. However, on May 27, the same day the Battle of Hanover Court House was fought northeast of Richmond, Johnston learned that McDowell's corps had been diverted to the Shenandoah Valley and would not be reinforcing the Army of the Potomac. He decided against attacking across his own natural defense line, the Chickahominy, and planned to capitalize on the Union army's straddle of the river by attacking the two corps south of the river, leaving them isolated from the other three corps north of the river.
If executed correctly, Johnston would engage three quarters of his army (22 of its 29 infantry brigades, about 51,000 men) against the 33,000 men in the III and IV Corps. The Confederate attack plan was complex, calling for the divisions of A. P. Hill and Magruder to engage lightly and distract the Union forces north of the river, while Longstreet, commanding the main attack south of the river, was to converge on Keyes from three directions: six brigades under Longstreet's immediate command and four brigades under D. H. Hill were to advance on separate roads at a crossroads known as Seven Pines (because of seven large pine trees clustered at that location); three brigades under Huger were assigned to support Hill's right; Whiting's division was to follow Longstreet's column as a reserve. The plan had an excellent potential for initial success because the division of the IV Corps farthest forward, manning the earthworks a mile west of Seven Pines, was that of Brig. Gen. Silas Casey, 6000 men who were the least experienced and equipped in Keyes's corps. If Keyes could be defeated, the III Corps, to the east, could be pinned against the Chickahominy and overwhelmed.
The complex plan was mismanaged from the start. Johnston chose to issue his orders to Longstreet orally in a long and rambling meeting on May 30. The other generals received written orders that were vague and contradictory. He also failed to notify all of the division commanders that Longstreet was in tactical command south of the river. (This missing detail was a serious oversight because both Huger and Smith technically outranked Longstreet.) On Longstreet's part, he either misunderstood his orders or chose to modify them without informing Johnston. Rather than taking his assigned avenue of advance on the Nine Mile Road, his column joined Hill's on the Williamsburg Road, which not only delayed the advance, but limited the attack to a narrow front with only a fraction of its total force. Exacerbating the problems on both sides was a severe thunderstorm on the night of May 30, which flooded the river, destroyed most of the Union bridges, and turned the roads into morasses of mud.
Battle.
The attack got off to a bad start on May 31 when Longstreet marched down the Charles City Road and turned onto the Williamsburg Road instead of the Nine Mile Road. Huger's orders had not specified a time that the attack was scheduled to start and he was not awakened until he heard a division marching nearby. Johnston and his second-in-command, Smith, unaware of Longstreet's location or Huger's delay, waited at their headquarters for word of the start of the battle. Five hours after the scheduled start, at 1 p.m., D.H. Hill became impatient and sent his brigades forward against Casey's division.
Hill's division, some 10,000 men strong, came charging out of the woods. The 100th and 81st New York regiments had been placed up front as heavy skirmish lines, and Hill's assault rolled completely over them. Casey's line, manned by inexperienced troops, buckled with some men retreating, but fought fiercely for possession of their earthworks, resulting in heavy casualties on both sides. The Confederates only engaged four brigades of the thirteen on their right flank that day, so they did not hit with the power that they could have concentrated on this weak point in the Union line. Casey sent a frantic request for help, but Keyes was slow in responding. Eventually the mass of Confederates broke through, seized a Union redoubt, and Casey's men retreated to the second line of defensive works at Seven Pines. During this period, both of the high commanders were unaware of the severity of the battle. As late as 2:30 p.m., Heintzelman reported to McClellan, still sick in bed, that he had received no word from Keyes. Johnston was only ;templatestyles src="Fraction/styles.css" / ;2+1⁄2 miles from the front, but an acoustic shadow prevented him from hearing the sounds of cannons and musketry and he and his staff did not know the battle had begun until 4 p.m. Hill, whose four brigades had been fighting alone for almost four hours, sent a message to Longstreet requesting reinforcements, but Longstreet sent forward only Richard Anderson's brigade. Brig. Gen Robert Rodes went down wounded in the desperate fighting around Seven Pines. Col. John B. Gordon of the 6th Alabama, a future major general, took over command of Rodes's brigade. Most of the officers in the 6th Alabama went down, although Gordon himself survived the battle without an injury despite his clothing and canteen being pierced by several bullets. Gordon also glimpsed his 19-year-old brother Augustus, a captain in the regiment, lying among a pile of dead and dying men with a chest wound, but with the battle raging, had no time to stop and tend to him (Augustus Gordon ultimately survived his injury). Rodes' brigade in total lost more than 50% of its strength. Also wounded was Brig.
Gen Gabriel Rains, a few days shy of his 59th birthday and one of the oldest officers in the Army of the Northern Virginia. Command of his brigade devolved on Col. Alfred Colquitt of the 6th Georgia, who would eventually be appointed permanent commander of the brigade.
The Army of the Potomac was accompanied by the Union Army Balloon Corps commanded by Prof. Thaddeus S. C. Lowe, who had established two balloon camps on the north side of the river, one at Gaines's Farm and one at Mechanicsville. Lowe reported on May 29 the buildup of Confederate forces to the left of New Bridge or in front of the Fair Oaks train station. With constant rain on May 30 and heavy winds the morning of May 31, the aerostats "Washington" and "Intrepid" did not launch until noon. Lowe observed Confederate troops moving in battle formation and this information was relayed verbally to McClellan's headquarters by 2 p.m. Lowe continued to send reports from the "Intrepid" via telegraph the remainder of May 31. On June 1, Lowe reported that the Confederate barracks to the left of Richmond as being free from smoke. McClellan did not follow up on this information with a counterattack by his corps north of the Chickahominy River.
Around 1:00 p.m., Hill, now strengthened by the arrival of Richard Anderson's brigade, hit the secondary Union line near Seven Pines, which was manned by the remnants of Casey's division, the IV Corps division of Brig. Gen. Darius N. Couch, and Brig. Gen. Philip Kearny's division from Heintzelman's III Corps. Hill organized a flanking maneuver, sending four regiments under Col.