The fall of 1861 is bereft of major fighting until Union Major Gen. George B. McClellan gets a disastrous battle going – by telegram.

Oct. 21, 1861, witnesses a badly coordinated attempt by Union forces to cross in boats from Maryland to the Confederate-held Virginia side of the Potomac River, northwest of Washington. Their aim: to seize a key railroad juncture at Leesburg, Va. But Union forces will get no further than the steep Virginia slope of the Potomac riverbank at the Battle of Ball’s Bluff.

It all began with a line in a seemingly innocuous McClellan telegram to a subordinate, Brig. Gen. Charles P. Stone. McClellan advises Stone, commander of troops along the Potomac, to “keep a good lookout upon Leesburg,” adding “perhaps a slight demonstration on your part would have the effect to move them.”

Stone obliges by sending two Union companies across the river the night of Oct. 20, 1861. They scale the bluff and report back that it’s a dangerous, steep slope. The next day, thousands of Union troops begin crossing, their incursion begun.

But Confederates above on the heights at Ball’s Bluff fiercely counterattack. Heavy Confederate cannon and rifle fire drives the green federal forces back down the bluff, many splashing mortally wounded and bleeding into the river. Others drown trying to swim away in uniform.

When it’s over, hundreds of Union troops are dead and hundreds more are missing or taken prisoner – out of roughly 1,780 ill-trained Union troops seeing their first action. A leader of the Union attack, Col. Edward D. Baker, who served in the U.S. Senate from Oregon, is killed. Baker is a good friend of President Abraham Lincoln, and the Union rout causes such an uproar in Washington that a congressional oversight committee is formed for the conduct of the war.