I recently read the new Gödel biography Journey to the Edge of Reason: The Life of Kurt Gödel and it was pretty clear that Von Neumann played a key role in getting Gödel out of Austria just prior to WWII. Gödel had been a visiting lecturer at the IAS at Princeton off and on in the 30s but probably due to his mental illness he would go back to Austria often with little notice - which didn't put him in good stead with IAS administration. In 1938 Gödel applied to teach at the University of Vienna but was turned down (Though not Jewish, he was considered to be too tied to what was labelled "Jewish science"). He was about to be conscripted into the German army which would have been a disaster given his many health problems. When Von Neumann became aware of Gödel's dire situation he lobbied his many powerful contacts in DC to come to Gödel's aid. Through diplomacy the Germans eventually allowed Gödel to leave under the condition that he would have to come back to serve in the army. He barely made it out in late '39 and probably wouldn't have without Von Neumann's intervention.