When you approach the road, send scouts ahead to ascertain if the invading troops have passed that way.

Should they have passed, take a concealed route and get ahead of them.

On ascertaining the locality of the troops, proceed at once to annoy them in every possible way.

Use every exertion to stampede their animals and set fire to their trains.

Burn the whole country before them and on their flanks.
Keep them from sleeping, by night surprises; blockade the road by felling trees, or destroying river fords where you can.