Respuesta :

On July 21, 1861, Union and Confederate armies clashed near Manassas Junction, Virginia, in the first major land battle of the American Civil War.

Answer:

Prince William County, Virginia

Explanation:

The first major battle of the Civil War was the First Battle of Manassas, also known as the First Battle of Bull Run. The battle took place in Prince William County, Virginia, near Manassas Junction on July 21, 1861, and resulted in a Confederate victory. The armies of both sides were disorganized and lacked training. However, both were also shocked by the fierce fighting and the number of casualties.