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.
It's not specifically Roman, but the time frame is similar: I recommend Donald W. Engels, Alexander the Great and the Logistics of the Macedonian Army, University of California Press, 1978.
The short version: Alexander and his generals had an extremely keen grasp of the logistical requirements of his army. He would send out advance detachments that negotiated the surrender of towns, oases and enemy supply depots and secured the provisions there. Most towns bowed to the inevitable extremely quickly. (After all, the alternative was to resist and be slaughtered, because the next Persian army would be far away, and busy not getting slaughtered itself.)
The book is also good in its discussion and calculation of how well ox carts can actually supply an army on the march. The answer is: not much, once you note that the oxen have to pull their own fodder as well.
I suggest you read Part III of Just Deserts: Roman Military Operations in Arid Environments (108 BC-AD 400) (Melissa Beattie, 2011, MPhil thesis from Cardiff University). It has a lot of good points about Roman and overall desert logistics and might be exactly what you need. I'll link to a pdf or you can search for yourself on google.List of site sources >>>