The conspirators were two of Burnside's own officers: Brigadier Generals John Newton and John Cochrane, division and brigade commanders in the VI Corps. The day after New Year's 1863, the pair took leave and traveled to Washington, D.C., intending to warn Congressional defense committee leaders that the Army of the Potomac was falling apart. They forgot Congress was in recess for the holidays. Cochrane, a former congressman himself, used his political connections to reach Secretary of State William H. Seward, who arranged a meeting with Lincoln. Newton tried to explain that the troops had lost all confidence in Burnside, but his wording was vague -- he later admitted he could not bring himself to say directly that the privates had no faith in their commanding general. Lincoln, who had seen plenty of scheming officers, remained skeptical. But the damage was done. The president now knew Burnside's plans and distrusted his army's cohesion.

When Burnside learned of the leak, he stormed to the White House. Lincoln told him two anonymous generals had revealed his strategy and the army's deteriorating condition. Burnside demanded they be court-martialed. General-in-Chief Henry Halleck agreed. But Lincoln pressed the real issue: a dangerous disconnect between the commanding general and his subordinates. In a private conversation, Burnside went further, denouncing both Secretary of War Edwin M. Stanton and Halleck, arguing that replacing them both would serve the nation. He then offered to resign his command entirely. Lincoln talked him out of it. Burnside was already desperate to restore his reputation after the catastrophic Battle of Fredericksburg the previous month, where waves of Union soldiers had been slaughtered charging fortified Confederate positions on Marye's Heights. He would try again -- this time upstream.

Burnside revised his plan. Instead of crossing the Rappahannock south of Fredericksburg, he would move upstream to U.S. Ford, due north of the Chancellorsville crossroads. On January 20, 1863, the army began to move. By nightfall, rain was falling. By the morning of the 21st, the roads had become a quagmire. Fifteen pontoon boats already sat in the river, nearly spanning it, with five more needed to complete the bridge. But the moment Burnside ordered his artillery forward, the heavy guns churned the soaked earth into a mortar bed. All day, men hauled and heaved in the downpour while cannon, caissons, and supply wagons sank axle-deep in mud. January 22 brought no relief -- the storm only intensified. Across the swollen Rappahannock, Lee's Confederates had ample time to line the opposite bank. Confederate sharpshooters peppered away at the struggling Federals, but Lee made no serious attempt to interfere. He had every reason to hope Burnside would actually manage to cross -- with a flooded river at his back, the Union Army would have been trapped.

Burnside finally accepted reality. He gave the order to retire, and the Army of the Potomac slogged back to its winter quarters near Falmouth. The Mud March was over. It had lasted three days and accomplished nothing except to confirm everything Newton and Cochrane had told the president. Morale, already shattered by Fredericksburg, collapsed entirely. Within days, Lincoln relieved Burnside of command and replaced him with Major General Joseph Hooker. It was Burnside's final act as leader of the Army of the Potomac. The ground along the Rappahannock where his army foundered lies in Stafford and Spotsylvania Counties, still wooded and rolling, still prone to the winter storms that turned Virginia's clay roads into swamps. The episode proved that in war, the enemy you cannot see -- rain, mud, dissent within your own ranks -- can defeat you as surely as the one across the river.