Union forces changed leadership due to mistakes in maneuvers.
The position of commander-in-chief of the Union Army was occupied, during the war, by the following generals:
Winfield Scott: from July 5, 1841 to November 1, 1861;
George B. McClellan: from November 1, 1861 to March 11, 1862;
Henry W. Halleck: from July 23, 1862 to March 9, 1864;
Ulysses Simpson Grant: from March 9, 1864 to March 4, 1869.
Scott was a former veteran of the Mexican-American War and because of his age he could not perform his duties properly. The war did not go well for the north during the first two years, and many were blamed for the poor qualities of strategist and the excessive caution of Scott's successor, Major General George B. McClellan. McClellan led the disastrous campaign of the peninsula and was replaced by Halleck as commander-in-chief as a result of the poor results. Although popular among the soldiers, McClellan was relieved of his position because of his excessive caution and controversial relationship with his superior, the president of the United States, Abraham Lincoln, being succeeded by Henry W. Halleck, who was preceded by very favorable reports from the western theater, but he was more an administrator than a planner and commander in chief.
Ulysses Grant was the last commander-in-chief of the Union Army. When he was appointed in March 1864 as the new commander-in-chief of the Union Army and Lieutenant General, he had already achieved fame on the occasion of his victories.
Grant supervised the Army of the Potomac (which was formally led by his subordinate, Commander General George G. Meade) in delivering the final hits to the Confederacy through the decisive defeats of the Confederate forces in a series of hard-fought battles in Virginia, culminating in the conquest of the city of Richmond, the capital of the Confederacy.
