B)They split their small, outnumbered army into two forces.
The Battle of Chancellorsville (April 30 to May 6, 1863) is looked upon as General Robert E. Lee’s greatest Civil War victory for the Confederate side. The Union army was almost twice the size of Lee's Confederate forces. Splitting his troops caught the Union side by surprise.
It was a costly victory for the Confederate side, however. While the Union suffered over 17,000 casualties, Lee's armies also had a high casualty rate of nearly 13,000 men. And one of those casualties was General Thomas “Stonewall” Jackson, who was killed by friendly fire in the final stages of the battle.