The common notion is that Japan surrendered in WW2 as a result of two successive nuclear bombings. However one fact that people tend to overlook is that hours prior to the bombing of Nagasaki, USSR declared war on Japan and invaded Manchuria. Was this invasion a more decisive factor than the bombings themself?
This is a fun question, because it's one of those where reasonable people can look at the evidence and come to quite different conclusions. The short answer is "maybe!" and the longer answer is "it depends." Lots on this in our FAQ, but you may be interested in these answers in particular: