President Lincoln wanted to know how much progress Gen. George B. McClellan was making in crossing the Potomac River into Loudoun County, Va. on October 29, 1862 and more importantly, what was his assessment of the enemy. The hastily scrawled letter to McClellan is now for sale for $100,000 from the Raab Collection in Philadelphia.

The letter is important, not only because it was written by Lincoln, but because it appears to be the last communication the president had with his famously slow-moving general before he fired him for not pursuing the retreating Confederate army after the Union victory at the Battle of Antietam on Sept. 16 to 18. McClellan delayed his pursuit until the end of October.

The letter, which had belonged to an anonymous private collector, reads, “Your dispatches of night before last, yesterday & last night, all received. I am very much pleased with the movement of the Army. When you get entirely across the river let me know. What do you know of the enemy?”

McClellan later ran for president against Lincoln and lost. The man Lincoln eventually appointed to run the war, Ulysses S. Grant, was elected to the office in 1868.

A spokesman for the dealer said the letter was available for purchase as of 9 a.m. this morning and they expected a great deal of interest in it.