Question

How did the First Battle of Bull Run/ First Battle of Manassas change opinions about the war?

Answer 1

Many thought the war would be over quickly. Union opinion was for a strong direct attack that would finish the Secession. Bull Run showed that this would not be easily done.

Explanation:

The Anaconda Plan put forward by Winfield Scott was derided. Lincoln's overall strategy for the war was very like this plan.

General McClellan was an early advocate of the direct attack. He took over command when General Scott retired. McClellan's moves when he commanded the Union Army and the Army of the Potomac reflected this belief in the direct attack on Richmond would decide the war.

The War eventually turned into a war of attrition.