What If the Atom Bombs Hadn't Succeeded?

What would've happened if Little Boy and Fat Man hadn't pounded Japanese morale into submission during World War 2?

Operation Downfall, that's what.

A plan was drafted for a massive Allied invasion of Japan. This wasn't going to be an easy feat, as only a few of their beaches would've been suitable for landing. Thus, the anticipated casualties of this proposed invasion were staggering:

In a study done by the Joint Chiefs of Staff in April, the figures of 7.45 casualties/1,000 man-days and 1.78 fatalities/1,000 man-days were developed. This implied that a 90-day Olympic campaign would cost 456,000 casualties, including 109,000 dead or missing. If Coronet took another 90 days, the combined cost would be 1,200,000 casualties, with 267,000 fatalities.

And another estimate:

A study done for Secretary of War Henry Stimson's staff by William Shockley estimated that conquering Japan would cost 1.7 to 4 million American casualties, including 400,000 to 800,000 fatalities, and five to ten million Japanese fatalities. The key assumption was large-scale participation by civilians in the defense of Japan.

Not that I'm supporting nuclear warfare here, but thank goodness the Japs surrendered when they did.