Scorched earth
A scorched-earth policy is a military strategy that aims to destroy anything that might be useful to the enemy while it is advancing through or withdrawing from a location. Any assets that could be used by the enemy may be targeted, for example food sources, water supplies, transportation, communications, industrial resources, and even the locale's people themselves.
Flying column
In the 1920s Defence Scheme No. 1, the proposed Canadian response to an invasion by the United States, Lt. Col. James "Buster" Brown suggested "immediate dispatch of flying columns on the declaration of war" in order to counter-invade across the border and enact a scorched earth policy, forcing the USA to divert military resources towards the defense of its northern cities.