Thoreau argues that individuals should not permit governments to overrule or atrophy their consciences, and that they have a moral duty to avoid allowing a government to make them the agents of injustice. Thoreau was motivated to write this essay by his disgust with the U.S. system of enslavement and the illegal land grab commonly referred to in the U.S. as the Mexican-American War (1846-1848), and in Mexico as the Intervención Estadounidense en México (U.S. intervention into Mexico).