Hi there, this is not to discourage any further answers, but this is a fairly popular question here. These are some answers taken from our FAQ/wiki; look under WWII -- The Atomic Bombs. Link here.

Did the US have to nuke Japan in WWII? -- submitted 5 months ago, 6 comments. Note The first comment there is, like this one, a compilation of past posts that could be useful to you. This comment in particular is a great summation of the options.

Would the Japanese have likely agreed to total unconditional surrender after just a "warning shot" pf the atomic bomb? -- submitted 2 years ago, 36 comments

What happened to the Japanese political/military landscape between August 6th, 1945 (the day that Little Boy was dropped on Hiroshima) and August 15th, 1945 (the day they surrendered). How did they come to the decision that surrender was the best option, and was there much disagreement? -- submitted 1 year ago, 223 total comments

If you see anything interesting in those old threads, feel free to tag the user in a comment here and they should get an alert (ex: hey /u/jschooltiger, can you tell me more about ...)

Thanks!