On this day in 1862, Abraham Lincoln cashiered General George B. McClellan for the second and last time. Lincoln had been angry for some time with McClellan, whose victories typically seemed to result from happenstance, while his failures all appeared to be the result of hard work.

In the days leading to Antietam, McClellan had, for example, stumbled upon a detailed accounting of Robert E. Lee’s plans for his Army of Northern Virginia. And yet, because of his pathological cautiousness, McClellan’s federal troop had not routed their rebel foes at the war’s bloodiest battle. The Union, despite McClellan’s good fortune, narrowly carried the day.

After Antietam, Lincoln took a massive political risk, issuing his Preliminary Emancipation Proclamation. Eager for more victories to raise morale and provide political cover, Lincoln practically begged McClellan to pursue Lee’s battered army. McClellan responded, time again, by noting that his Army of the Potomac was foot-sore and hungry. In mid October, the President, taking note of the fact that Lee’s men were in far worse shape than were McClellan’s, wrote the general, gently asking him, “Are you not over-cautious when you assume that you can not do what the enemy is constantly doing?” Lincoln warned that McClellan did not have time to dither and instead had to move quickly to engage the enemy.

McClellan ignored him. He then discovered a new excuse for inactivity: his pack animals, like his men, were exhausted. Exasperated, Lincoln replied: “Will you pardon me for asking what the horses of your army have done since the battle of Antietam that fatigues anything?” Finally, on October 26, the Army of the Potomac crossed its namesake river. It was too late. Lee had been reinforced. The Army of Northern Virginia remained intact. Richmond stood just out of reach.

Lincoln fired McClellan, noting that the general had a case of “the slows.” McClellan’s war career was over. He turned to politics, faring about as well as he had on the battlefield. McClellan lost the 1864 election to Lincoln, who, by that time, had cycled through a series of generals before finally tapping U.S. Grant to command the Union’s military. Grant may not have been fast. But nobody ever claimed, as Lincoln had of McClellan, that he was a “stationary engine.”