Why did the Union Army attack at Bull Run?

They were hoping to end the war as quickly as it started

The Civil War had begun a few months earlier at the Battle of Fort Sumter. Both the North and South were eager to finish the war. The South figured that with another major victory the North would give up and leave the newly formed Confederate States of America alone. At the same time, many politicians in the North thought that if they could take the new Confederate capital city of Richmond, Virginia the war would be over quickly. Union General Irvin McDowell was under considerable political pressure to march his inexperienced army into battle. He set up a plan to attack the Confederate force at Bull Run