1861
First Battle of Bull Run (First Manassas)
The setting
Prince William County, Virginia, United States
Rolling farmland, hills (Henry House Hill), and the Bull Run stream
Reveal the outcome
Recorded sideUnited States (Union)
Recorded resultdefeat
Confederate victory; disorganized Union retreat toward Washington
How the atlas explains it
Confederate reinforcements arriving by rail from the Shenandoah Valley and a firm stand on Henry House Hill (where Jackson earned the name "Stonewall") blunted the Union assault and turned the tide into a rout.
What followed
The first major land battle of the war; the Confederate victory shattered Northern hopes of a quick, easy end and revealed to both sides that the conflict would be long and costly.