Civilian casualties is the only thing that ends wars.
WWI had military carnage beyond belief and most of it was a total waste. Trench warfare with gas attacks. It went on like this almost endlessly, gain a little territory, loose a little territory. The population centers of Europe suffered very little.
In contrast WWII took so long because the battle field was so large. It stretched from Great Brittan on the west all the way to Japan on the other side of the world.
I'm not sure bombing Dresden and Berlin weakened Germany , it sure didn't stiffen it the way that the Battle of Britain stiffened the Brits. Hitler squandered the German military. The defense of Berlin was left to teens and old men.
Japan on the otherhand did surrender after the Decimation of Hiroshima and Nagasaki. Military estimates were that it would coust another 500,000 American lives to take the island.
Since my Dad was in the Navy sitting on Guam at the time, I have no remorse about the use of the atomic bomb.
I think a consideration should be to nuke Mecca during a holy week.
Kudos to your father and his bravery in serving. My dad arrived at Guam a couple of days after Japan surrendered. Theirs is the greatest generation.