Perhaps I am mistaken, but the United States appears to be the only country in the world where a large portion of the citizens celebrate and venerate those who attempted to secede from the nation generations after the end of the war. This appears to be the result of the relatively lenient treatment of the leadership of the Confederate States following the end of the war, allowing the further propagation of the sentiments that led to the Civil War to continue to spread among the population of the Southern States. If this is the case, why didn't the United States government impose harsher punishments on those people? If I'm totally mistaken about the roots of the modern fascination in the South with the "heritage" of the rebels, please explain the roots of the Southern celebration of the losing side of a war.
The Union was much more interested in getting the war out of the way and restoring the South to being a functional part of the country as opposed to punishing it and increasing animosity towards the North. After all the war had caused the Union to do a considerable amount of damage to the industry and population of its own country, and the smartest thing to do was try and mend relationships and bury the hatchet as quick as possible while they got the nation back on its feet.
Because Reconstruction was already very rough on the south to the point it led to blowback. Lincoln before his death preferred a much easier piece.