Despite the fact that Confederate spy Thomas Nelson Conrad had obtained documents describing McClellan's battle plans from a double agent in the War Department, McClellan was initially successful against the equally cautious General Joseph E. Johnston, but the emergence of the more aggressive General Robert E. Lee turned the subsequent Seven Days Battles into a humiliating Union defeat.

The first heavy fighting of the campaign occurred during the Battle of Williamsburg in which the Union troops managed some tactical victories, but the Confederates continued their withdrawal.

[8] During the summer and fall, McClellan brought a high degree of organization to his new army, and greatly improved its morale by his frequent trips to review and encourage his units.

"[11] On January 12, 1862, McClellan revealed his intentions to transport the Army of the Potomac by ship to Urbanna, Virginia, on the Rappahannock River, outflanking the Confederate forces near Washington, and proceeding 50 miles (80 km) overland to capture Richmond.

However, McClellan came under extreme criticism from the press and the Congress when it was found that Johnston's forces had not only slipped away unnoticed, but had for months fooled the Union Army through the use of Quaker Guns.

[14][15][16][17] A further complication for the campaign planning was the emergence of the first Confederate ironclad warship, CSS Virginia, which threw Washington into a panic and made naval support operations on the James River seem problematic.

Although McClellan was assuaged by supportive comments Lincoln made to him, in time he saw the change of command very differently, describing it as a part of an intrigue "to secure the failure of the approaching campaign.

In Richmond, General Robert E. Lee had returned from work on coastal fortifications in the Carolinas and on March 13 became the chief military adviser to Confederate President Jefferson Davis.

The first, about 12 miles (19 km) north of Fort Monroe, contained infantry outposts and artillery redoubts, but was insufficiently manned to prevent any Union advance.

Gen. Erasmus D. Keyes made initial contact with Confederate defensive works at Lee's Mill, an area McClellan expected to move through without resistance.

[41] For the remainder of April, the Confederates, now at 57,000 and under the direct command of Johnston, improved their defenses while McClellan undertook the laborious process of transporting and placing massive siege artillery batteries, which he planned to deploy on May 5.

Confederate counterattacks, directed by Maj. Gen. James Longstreet, threatened to overwhelm Hooker's division, which had contested the ground alone since the early morning while waiting for the main body of the army to arrive.

Gen. Winfield S. Hancock's 1st Brigade of Baldy Smith's division, which had marched a few miles to the Federal right and crossed Cub's Creek at the point where it was dammed to form the Jones's Mill pond, began bombarding Longstreet's left flank around noon.

Splitting his command, Early led two of his four regiments through the woods without performing adequate reconnaissance and found that they emerged not on the enemy's flank, but directly in front of Hancock's guns, which occupied two abandoned redoubts.

[56][58] As a second brigade followed Hood on his left, the Union troops retreated from the woods to the plain before the landing, seeking cover from the fire of Federal gunboats.

Whiting employed artillery fire against the gunboats, but his guns had insufficient range, so he disengaged around 2 p.m. Union troops moved back into the woods after the Confederates left, but made no further attempt to advance.

Exercising his direct powers as commander in chief, Lincoln ordered naval bombardments of Confederate batteries in the area on May 8 and set off in a small boat with his two Cabinet secretaries to conduct a personal reconnaissance on shore.

[59] After the Confederate garrison at Norfolk was evacuated, Commodore Josiah Tattnall III knew that CSS Virginia had no home port and he could not navigate her deep draft through the shallow stretches of the James River toward Richmond, so she was scuttled on May 11 off Craney Island to prevent her capture.

The Confederate defenders, including marines, sailors, and soldiers, were supervised by Cammander Ebenezer Farrand of the navy and by Captain Augustus H. Drewry of the army, the owner of the property that bore his name.

[68] Rodgers reported to McClellan that it was feasible for the Navy to land troops as close as 10 miles (16 km) from Richmond, but the Union Army never took advantage of this observation.

Second, McClellan anticipated the arrival of McDowell's I Corps, scheduled to march south from Fredericksburg to reinforce his army, and thus needed to protect their avenue of approach.

[75][71] While skirmishing occurred all along the line between the armies, McClellan heard a rumor that a Confederate force of 17,000 was moving to Hanover Court House, north of Mechanicsville.

They had departed from Gordonsville to guard the Virginia Central Railroad, taking up position at Peake's Crossing, 4 miles (6.4 km) southwest of the courthouse, near Slash Church.

[83][82][81][84] A greater impact than the actual casualties, according to Stephen W. Sears, was the effect on McClellan's preparedness for the next major battle, at Seven Pines and Fair Oaks four days later.

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.

On Longstreet's part, he either misunderstood his orders or chose to modify them without informing Johnston, changing his route of march to collide with Hill's, 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.

Johnston went forward on the Nine Mile Road with three brigades of Whiting's division and encountered stiff resistance near Fair Oaks Station, the right flank of Keyes's line.

To buy time to complete the new defensive line and prepare for an offensive, Lee repeated the tactic of making a small number of troops seem larger than they really were.

[108] The second phase of the Peninsula campaign took a negative turn for the Union when Lee launched fierce counterattacks just east of Richmond in the Seven Days Battles (June 25 – July 1, 1862).