In the chapter 'The Beginning of the War' of his autobiography Going Solo, Roald Dahl recounts his role in stopping the German population of Dar es Salaam from fleeing to Portuguese East Africa (the nearest neutral territory). There was a considerable population of Germans in the city because of its former status as a German colony. Dahl writes that only a few hours after the declaration of war, a large and organised convoy of Germans took the coastal road heading south. They were stopped by Dahl and his platoon after the leader of the German convoy was shot.
Why did the German population wait until war had been declared before fleeing?
In August 1939 the prospect of war was all but certain, as evidenced by the organisation of the German convoy out of Dar es Salaam. By waiting until war had been declared, the British could legitimately stop and intern them as enemy aliens, but had they left just one day earlier, could they not have made their way unimpeded to Portuguese East Africa? Or is it all just simply a case of Dahl using artistic license?
I have tried looking for a secondary source to verify Dahl's account, but all I seem to find is (lots) of information about the East African campaign.
EDIT In the comments it has been asked: 'How would they know that Poland would be invaded soon?' The German population of Dar es Salaam would not have known exactly how and when the war would start, but I really do not think it can be reasonably believed that they were unaware of the distinct possibility of the imminent outbreak of war. For instance, Dahl recounts what an Army captain told him: 'The prison camp is ready, and the Germans know it is ready.'
The same comment also says: 'After Germany got the Ruhr, Austria, Sudetenland, Memel, they could believe that the UK/France would back down again.' This is a good point and perhaps the start of an answer?
