I'm writing a novel set in the third century. A general is marching his army through the middle of the Syrian Desert. How did Roman armies with tens of thousands of soldiers survive in the arid wasteland. How did they get food and water?
I've tried to research on this specific topic, but I couldn't find much, only anecdotes about Antony, Crassus, or Trajan. But nothing about how they specifically survived in the desert, only that it was hard and that they somehow got through it.