The question of morale is relevant in the East, where the Union is suffering a lot of casualties. Except that the AoP and the AoJ were supported by the Navy, the Overland Campaign would have become a death march, not a march to victory.Not so sure of that. Yes the Union Navy played an important role but War's are won by seizing and holding enemy territory. Some on this forum have argued that because of the EP Union Army morale collapsed but they can not explain why then the Confederacy failed to win the ACW in 1863.
It was not 1863 that would have seen the results of sagging morale, it would be 1864...before the EP, there had been a new wave of recruiting that kept the AoP going through Gettysburg, and that was the last fight of the Great Grand Army of the Republic; afterwards the AoP was a collection of men in uniform by whatever means it took. It would not have taken much different for the Union to have been completely unsuccessful in 1864 on the ground.