In part three of Fahrenheit 451, where does the war end and what happens to the city?
We're not sure where the war ends; it is implied that after their city is bombed, that that particular war has ended. However, we don't know if other cities were wiped out, we don't know if further strikes are planned, and we don't know the extent and depth of the war. Throughout the book, Montag implied that war was a part of their everyday lives for as long as he could remember. There were always jet planes going in the skies, a constant reminder of the war. Then, Mildred's friends speak of their husbands and friends always being gone to fight, and die. So, war was a huge part of Montag's society; possibly, it ended with the bombing of their city, possibly not. Considering the dramatic implications of Granger, Montag and their crew going to restart society and rebuild, we can assume that perhaps the war was over, and Montag and others like him will be the new leaders in establishing society again out of the ruins.
The city itself is demolished completely by bombs. It is destroyed by jet bombers, and goes up in ashes; this implies a nuclear bomb. It would need to be something very powerful to just wipe out a city in one swipe, and Bradbury describes the ruins as "a heap of baking powder." So, it wasn't wiped out by typical explosions that caused firestorms; it just obliterated everything. Perhaps, in this futuristic society, it was a bomb that had that power. In any case, the city is destroyed. I hope that those thoughts helped; good luck!