No first the machine then once one country runs out of resources and machines they will either surrender or more machines will start bombing them until they do. Yes people will still die but think of Japan and nukes. It will be much the same. You will realize oh damn drones can come in and basically kill all day long and we ran out of drones to defend this. Guess we surrender or die. So yea people still die but first will be a resource war followed by a short lived hopeless defence. Technological superiority will allow one country to lose very little life as it will be fought from thousands of miles away.