Which of the following is a true statement about the Second Battle of Bull Run?

It placed the Union capital in danger.

Explanation:

The Second Battle of Bull Run took place between August 29 and August 30, 1862, during the Civil War.

Both the Union's and the Confederacy's armies received news of the advance of the other group in the morning. Major General Pope launched a series of attacks in an attempt to break through the defense of the Confederacy. The Northern Army battled with Jackson's men until the afternoon and retreated.  

The next day, after observing the marching route of the Confederate Army, Pope mistakenly thought that they were retreating, and immediately ordered his subordinates, including McClellan’s army chase, that one or two divisions followed the Southern Army, while the other three were going to surround it, trying to trap it.

Unexpectedly, it turned out that the Southern Army was only deploying troops to extend the front and attempted to strike its flanks when the Northern Army attacked. The northern army's offensive troops were soon bombarded by the southern army. However, the North Army continued to move forward, attacking Jackson’s defense, and Longstreet took the opportunity to attack the North Army's left wing. After successfully attacking with Jackson, he attacked the center of the North Army, forcing Pope and his men to retreat towards Washington DC.

The victory encouraged the Southern Army to take the initiative to launch aggression towards the north, and the Maryland Campaign, aimed at reaching Washington DC, began soon.