Churchill’s arrogance in WWI (1914-1918) cost over 100,000 men their lives - I know some people will say “so what” to the loss of life - after all, we all know the “important” cause of WWI (I guess, making the world safe for dicators to come)... History is scary if you look it in the eye.
As for Abraham Lincoln, over half a dozen European countries abolished slavery without engaging in a bloodbath that killed over 600,000 men and ended with a 12 year occupation.