Battery:
"a grouping of artillery pieces for tactical purposes"
Battery A through F was the name given to 6 forts that made up the outer line of defense around the town of Corinth, MS built in the spring of 1862 by the Army Corps of Engineers.
Battery F played a pivotal role in stopping a surprise attack led by CSA Generals Earl Van Dorn, and Sterling Price. General William S. Rosecrans of the Union Army was told ahead of time to be ready for an attack and was able to move his troops closer to the town in time.
The Second Battle of Corinth as it came to be known lasted 3 days and was called the bloodiest battle in Mississippi the heaviest fighting in the Battle of Corinth occurred October 4th, 1862 (curiously 7 months from March 4th 7 being the number of batteries constructed for the inner line of Corinths defenses)