What if Napoleon had an A-bomb at Waterloo?
In his book Guns of the South (New York; Ballantine, 1992), Henry Turtledove speculates what might have happened had the Confederate army been equipped with Kalashnikovs in 1864.
Then I guess it wouldn't be his "Waterloo" any longer.
Our weapons systems, applied early in the battle, would ease our logistics load by wiping out most of the enemy within a week.
The rest of our efforts would be mop-up (pacification).