The Northern army faced multiple disasters that embarrassed Lincoln in both theaters of the war. Three main ones stood out and would forever be remembered in history. They were the Second Battle of Bull Run, Battle of Fredericksburg, and the Union's attempt to take Richmond.
The Second Battle of Bull Run was a huge embarrassment for Lincoln and the Union army. Leadership was atrocious and confusing for the Union side. Orders from Pope could not be followed which revealed the inability of Pope to assess his own army and meet its needs. It was mainly due to Pope’s inability to command that the Union lost. He misjudged the actions of Lee’s army which led to a disastrous end to the battle for the Union side. In the end Lee was able to push the Union back and move dangerously close to Washington.
It was the Battle of Fredericksburg that was the end for Union leader Burnside. He had been placed in charge after McClellan had been removed due to continual lack of performance and inability to deliver the Union what it needed. Burnside was a great planner, but when he got to Fredericksburg, his plans fell all apart. His boats were not in place where he needed them to cross the Rappahannock. By the time, he was able to cross the river, Lee was in place on the other side. Beforehand, there were no Confederate soldiers to stop them. He was now without the advantage. The Union found itself walking into a version of hell as the battle commenced along with the loss of it. Burnside was driven back and the blood was heavy.
Lincoln wanted the Union army to take Richmond and hopefully end the war. Moving toward the Confederate capital, Jackson blocked them in the Shenandoah Valley where numerous battles were fought. The Union lost and was pushed back away from its target of Richmond. Lincoln had to admit defeat in being able to beat the South just by surging forward.
Both sides in the war faced embarrassments, but in order to win the war, Lincoln had to show the public that the Union was capable.