Lincoln was a traitor. He instituted the first military draft (conscription slavery) to fight his civil war ("war between the states", "the war of northern aggression"). His war was not about slavery. He like other corrupt politicians, needed a "popular cause" such as that to hang his campaign on.
Another reason was to "preserve the union". The states, under the Constitution, had the right to secede. The states, under the Constitution, had "appointed" the Federal government to handle a certain LIMITED number of jobs, such as providing a common defense.
For many reasons, not room here to discuss, many of the southern states wanted out.
As with all politicians, power is the goal. Pressure had been building for decades to get the Federal government more power. Lincoln did it, in "spades". He turned the country from a union of united states (no upper case letters) into the United States, where the ultimate power no longer lay with the states, but with a powerful Federal (central) government.
We see the results of that, today. There is no check on Federal power, and the states are mere franchises of the Federal government. Lincoln laid the groundwork for the abuses of all subsequent regimes, up to and including Bush, Clinton, Bush, Obama, not to mention both Roosevelts, Wilson, and others.