Final answer:
The strategy is called scorched-earth strategy and it involves burning fields and killing livestock to deprive the enemy of resources.
Step-by-step explanation:
The strategy that involves burning fields and killing livestock to prevent the enemy army from living off the land is called scorched-earth strategy. This tactic aims to deprive the enemy of valuable resources and weaken their ability to sustain themselves during the conflict. An example of this strategy can be seen during the Boer War when the British adopted a scorched-earth policy in response to Boer guerrilla tactics, destroying Boer homes, farms, and livestock to deny them food and shelter. Another example is when Chiang Kai-shek adopted a scorched-earth strategy during the Second Sino-Japanese War, retreating inland and burning villages to slow down the invading Japanese forces.