This. Specifically, the mention of Caesar reminded me of the beginning of the Gallic wars, when the Helvetii tried something similar: http://classics.mit.edu/Caesar/gallic.1.1.html

> When they thought that they were at length prepared for this undertaking, they set fire to all their towns, in number about twelve - to their villages about four hundred - and to the private dwellings that remained; they burn up all the corn, except what they intend to carry with them; that after destroying the hope of a return home, they might be the more ready for undergoing all dangers.

Spoiler: It did not work out so great for them.