General History/What if Operation Valkyrie was a success?
How would have history played out if Operation Valkyrie was a success and Hitler was assassinated?
I suspect the Valkyrie conspirators would have been disappointed with their results, even if they had assassinated Hitler and had successfully taken over the German government. First, it's possible that even if they had killed Hitler, some other Nazi, like Hermann Goering or Heinrich Himmler, would have taken Hitler's place and the Nazi regime would have remained in place. But even if the Valkyrie conspirators had completely replaced the Nazi regime, I don't think they would have gotten what they wanted.
Most of the Valkyrie conspirators thought they could make peace with the US and Britain but continue the war against the Soviet Union. The western allies were, however, bound by treaty to not make a separate peace. Germany would have had to surrender to all of the allies or the war would continue. Also, the western allies were committed to the idea of unconditional surrender. The Valkyrie conspirators probably thought they could obtain reasonable terms, but this was an illusion. While the allies did not finalize their plans for post-war Germany until the Yalta Conference in February 1945, by the summer of 1944, they had a pretty good idea of what they would do. If Germany had surrendered in the summer of '44, Germany still would have been completely occupied by the allies, there would have been an intensive de-Nazification program, the German Army would have been disarmed and de-mobilized, there would have been war crimes tribunals, etc. I do not think the Valkyrie conspirators were prepared for all of that (except the de-Nazification). Twice in 25 years, Germany had started world wars. The allies were very determined to ensure that did not happen a third time. Germany would not have been left intact, and that is what the Valkyrie conspirators really wanted -- to get Germany out of the war with something still intact.