(A) ** The battle was off of a river known as Bull Run.
(B) There were bulls fighting in the battle.
(C) The opposing sides thought of each other as bulls.
(D) The bull was a mascot.
EXPLANATIONS BELOW
Concept note-1: -The Confederate Army of the Potomac (21, 883 effectives) under Beauregard was encamped near Manassas Junction where he prepared a defensive position along the south bank of the Bull Run river with his left guarding a stone bridge, approximately 25 miles (40 km) from the United States capital.
Concept note-2: -The first land battle of the Civil War was fought on July 21, 1861, just 30 miles from Washington-close enough for U.S. senators to witness the battle in person. Southerners called it the Battle of Manassas, after the closest town. Northerners called it Bull Run, after a stream running through the battlefield.
Concept note-3: -The First Battle of Bull Run, also known as the Battle of Manassas, marked the first major land battle of the American Civil War. On July 21, 1861, Union and Confederate armies clashed near Manassas Junction, Virginia.
Concept note-4: -Bull Run was the first full-scale battle of the Civil War. The fierce fight there forced both the North and South to face the sobering reality that the war would be long and bloody.
Concept note-5: -On July 21, 1861, in the first major land battle of the Civil War, a large Union force under General Irvin McDowell is routed by a Confederate army under General Pierre G.T. Beauregard.