Many historians fantasists argue that Southern states would likely have reunited with Northern states before the end of the 19th century had Lincoln allowed for a peaceful and constitutionally accorded caved in to unconstitutional secession.
Fixed it. The Confederate government was a government, not a collection of disgruntled guys meeting in basements. They got the war started to establish a country of their own in opposition to the United States. When was the last time a government ever decided to go out of business?
And even if the nation did eventually reunite, on whose terms would it have been? The secessionists' definitely. That would mean no civil rights laws, a Southern veto over legislation and no federal power to stand up to foreign governments.
Please understand, the rebel leaders weren't in favor of "the Constitution as it was." They were opposed to the Constitution of 1789 and to the results it could bring. They destroyed "the Old Republic" before Lincoln even got into the White House.
The whole slavery issue, which is the most disastrous mistake in U.S. history, should have been dealt with decisively at the time of ratification of the Constitution. Sane and ethical leaders like VA's Washington (our real greatest President) wanted to phase out slavery, starting with an end to the slave trade and it's exclusion from new territories. The extreme Southern states refused to accept any restrictions. Why? For the same basic reason Jorge and others want amnesty for Hispanic illegals: Blacks could be made to do "the work white Americans wouldn't do." Land was nearly free and abundant, so each white could have his own farm. No white would work as serf on a malarial plantation. So in order that an elite could enjoy an aristocratic lifestyle on the backs of others and "generate wealth," slavery was allowed to continue. The result was example of what happens when short-term economic considerations and greed triumph over ethics and national interest.
The smashing and grabbing was done by Sherman’s looters.