This vague question does not indicate which casualties. I am including a link below in the hopes you find an answer you are looking for.
They were dropped on the cities of Nagasaki and Heroshima. Harry S. Truman made the decision saying that it would shorten the war and lessen the U.S Casualties.
The synonym for casualties is deaths.
At least ~12,000 overall Allied casualties , German casualties were estimated at between 4,000 and 9,000 casualties .
The Russians admitted 300,000 casualties with 75,000 dead. Their true number of casualties was certainly much higher, perhaps double the official numbers. The German casualties were estimated at 100,000 military or paramilitary including Volksrum and Hitler youth, along with an additional 175,000 civilian casualties, for a total of 275,000. Again the numbers are most likely low. Some authoritative estimates place the combined number of casualties for all combatants at over 1,000,000. No matter what the true numbers were two facts stand out. Urban warfare which becomes house to house and street to street fighting is extremely expensive in lives and always leads to horrific casualty counts.
12,513 US casualties .
There were approximately 13,000 Union casualties at the Battle of Shiloh.
about 650,000 total casualties
Casualties of Peace was created in 1966.
About 50,000 casualties total. Union Casualties, 23,000 Confederate Casualties, 25,000
At the battle of Caporetto, the Central Powers had 20,000 casualties, while the Italian forces of the Allies had over 300,000 casualties! (That's a lot of casualties!)
According to the Department of Defense there have been approximately 4,500 Casualties on account of Operation Iraqi Freedom.
10,000 casualties of the union army 9,091 casualties of the south 29,495 men surrendered