Question

at the start of the battle of gettysburg, the union army
drove the confederates out of pennsylvania.
was forced into a defensive position.
broke through the confederate army’s line.
fought the confederate army to a stand-off.

Explanation:

At the start of the Battle of Gettysburg, the Union Army was forced into a defensive position. The Confederate Army had the initiative initially, and the Union forces had to quickly organize and take up defensive positions on key terrain like Cemetery Hill and Cemetery Ridge.

Answer:

was forced into a defensive position.