By the spring of 1863, the Federal Army of the Potomac had little to show for two years of campaigning across Virginia's blood-soaked countryside. Its most recent defeat at Fredericksburg in December 1862 had been little more than useless slaughter, and in its aftermath President Lincoln appointed a new commander, Gen. Joseph Hooker. Over the next months, Hooker revitalized his army of 134,000 men and soon devised a bold plan to force Robert E. Lee's Confederates out of their defenses around Fredericksburg. By stationing the rebels in front of the town while sending the bulk of his forces across the upstream fords of the Rappahannock River and its tributary the Rapidan, Hooker hoped to force Lee to fall back on Richmond.

Across the river, Gen. Robert E. Lee's underfed and poorly equipped Army of Northern Virginia had barely 60,000 men to hold the line of the Rappahannock against Hooker's formidable numbers. But the rebels possessed a cadre of brilliant leaders – most notably Lee and the already legendary Stonewall Jackson.

Once Confederate cavalry patrolling the rivers confirmed that Hooker had made a crossing upstream, Lee opted for the bold maneuver of dividing his forces in the face of the enemy. Leaving behind 9,000 men to watch the Union force at Fredericksburg, Lee marched west with the remainder of his army to confront Hooker. On May 1, 1863, sharp rebel attacks on the Federal vanguard caused Hooker to inexplicably lose his nerve and pull back to take up defensive positions around a small crossroads named Chancellorsville.

That night as Lee and Jackson were working...