Don’t forget Democrat party US Army General George B. McClellan in that equation. He wanted to replace Lincoln as president, and didn’t actually want to fight the Confederates, so endlessly delayed and screwed around. He also made his contempt of Lincoln well known, and was often insubordinate to him.
He wanted to negotiate with the Confederacy, not fight them.
When Lincoln fired him, he became the unsuccessful Democratic Party nominee opposing Lincoln in the 1864 presidential election, on a peace platform.
Democrats have always been the party of destruction and division. When Obama praises the Republican Lincoln it makes me cringe. I suspect 9/10 college graduates think Lincoln was a Democrat.