I just watched the U.S. Army Field Band play and sing the "Battle Hymn of the Republic". and yes it brought tears to my eyes. It always does that, just like watching the Victory at Sea episode covering Pearl Harbor, where I finally have been. Julia Howe wrote the lyrics after seeing a review of the Army of the Potomac in November of 1861. Not all of the verses are sung nowadays, but all are worth reading. George McClellan was a great organizer, I will concede that, but a failure as a battle commander. The Army of the Potomac never really had a commander that would call upon all of its efforts until U.S. Grant became basically the Army Commander in Chief. Yes, George Meade was the immediate commander, but Grant gave the orders to Meade for the army's movements and actions. Grant was the commander that would "never call retreat", and truly unleashed the "terrible swift sword" that was the Army of the Potomac. It was the grim, relentless fighting that finally broke the Army of Northern Virginia.
If you have never read Bruce Catton's series on the Army of the Potomac, at least read the final book, A Stillness at Appomattox, which covers the period of Grant as the effective commander. For understanding the background to the Civil War from a political angle, read his The Coming Fury, and for a single volume history of the Civil War, read This Hallowed Ground. Their was an enormous price in blood paid for emancipation. It is time we as a nation remember that.