Simplify the following text for a Grade 8 native English-speaking person.
Original: In the afternoon , Union Maj. Gen. Ambrose Burnside 's corps entered the action , capturing a stone bridge over Antietam Creek and advancing against the Confederate right .
Simplified: In the afternoon , Maj. Gen. Ambrose Burnside 's corps entered the action , capturing a stone bridge over Antietam Creek and advancing against the Confederate right .