They killed Lincoln but they couldn’t kill the abolitionist movement. Congress ratified three of the most progressive laws written in a century and the Freedman’s Bureau took to the job of enfranchising and rehabilitating millions of black ex-slaves in the subsequent decade.
Pick up a copy of W.E.B DuBois’s “The Souls of Black Folk”. What he describes is, at it’s heart, a revolution in how our country treated men and women of African descent. It set the foundation for the next century of civil rights and paved the way for a modern era in which the core racist underpinning of the country are totally upended.
That kind of fundamental change would not have been possible under a Breckinridge administration, nor would it have been possible if the Union had been crippled into submission at Gettysburg or Antitem.
Lincoln was the tip of the abolitionist spear and critical to what came after. But he was not alone. And he was by no means the most radical voice within his party. His martyrdom became the bloody shirt that Republicans rallied under long after the war had ended.
Wait, when you say Republicans, do you mean the organisation that Americans currently call the Grand Old Party, the GOP, the modern Republican Party? If so, I find it ironic that the party standing for freedom has evolved into the party that shields and encourages racists and criminals.