What impact did confederate victories seem to have on northern morale?

The answer is: Some questioned the war and Lincoln's leadership.

When the northern states battled the southern states in the civil war, the northern states have larger number of soldiers and more advanced weapons due to early industrialization.

Because of this, the northern citizens supported the cause with full confidence. After hearing that they manage to lost despite having the advantage, some questioned the war and lincoln's leadership.

a countries leader should be motivated by the common good of the country.