Okay but Lenin considered the US Civil to be good actually

But what a pedant, what an idiot would anyone be to deny on these grounds the immense, world-historic, progressive and revolutionary significance of the American Civil War of 1863-65!

The representatives of the bourgeoisie understand that for the sake of overthrowing Negro slavery, of overthrowing the rule of the slaveowners, it was worth letting the country go through long years of civil war, through the abysmal ruin, destruction and terror that accompany every war. But now, when we are confronted with the vastly greater task of overthrowing capitalist wage-slavery, of overthrowing the rule of the bourgeoisie—now, the representatives and defenders of the bourgeoisie, and also the reformist socialists who have been frightened by the bourgeoisie and are shunning the revolution, cannot and do not want to understand that civil war is necessary and legitimate.

https://www.marxists.org/archive/lenin/works/1918/aug/20.htm