Short answers, pulled from the story.
The Peninsula campaign was a Union operation intended to capture Richmond, the Confederate capital. Major General George B. McClellan transported 121,500 men by sea to Fort Monroe, Virginia, then advanced northwest up the Virginia Peninsula toward the city. The campaign ran from March to July 1862.
McClellan's advance stalled due to a combination of factors: Magruder's successful deception at Yorktown, faulty intelligence from detective Allan Pinkerton that led McClellan to believe he was outnumbered, the withholding of McDowell's corps for Washington's defense, and Robert E. Lee's aggressive counterattacks in the Seven Days Battles of June 25 to the 1st of July 1862.
General Joseph E. Johnston was wounded by a Union artillery shell fragment at dusk on the 31st of May 1862, during the Battle of Seven Pines. G. W. Smith assumed temporary command but made a poor impression on President Jefferson Davis. On June 1, Davis replaced Smith with Lee as commander of the Army of Northern Virginia.
On the 8th of March 1862, CSS Virginia attacked the Union wooden fleet at Hampton Roads, sinking USS Cumberland and USS Congress. Her continued presence forced McClellan to abandon his planned amphibious envelopment of Yorktown. She was scuttled on May 11 off Craney Island after Union troops occupied Norfolk and she had no home port.
The Battle of Williamsburg on the 5th of May 1862, engaged nearly 41,000 Union and 32,000 Confederate troops. Confederate casualties were 1,682 and Union losses were 2,283. The battle allowed Johnston's army to continue its withdrawal toward Richmond; McClellan called it a "brilliant victory," but the Confederate rearguard had achieved its purpose of buying time.
On the 15th of May 1862, Commander John Rodgers led a Union naval squadron up the James River toward Richmond. The USS Galena anchored within 600 yards of Fort Darling on Drewry's Bluff and took 45 hits over more than three hours, suffering 14 dead or mortally wounded and 10 injured. The fort, equipped with eight cannons including guns salvaged from CSS Virginia, halted the naval advance just 7 miles short of the Confederate capital.