Henry David Thoreau is the influential figure associated with the introduction of the concept of civil disobedience. In his essay "Civil Disobedience," written in 1849, Thoreau argued that individuals should prioritize their conscience over governmental laws when those laws are unjust. His work was inspired by his opposition to slavery and the Mexican-American War, and he emphasized nonviolent resistance as a moral obligation. Thoreau's ideas laid the foundation for future civil rights leaders, such as Martin Luther King Jr. and Mahatma Gandhi, who drew upon his philosophy to justify their nonviolent protests against oppressive regimes, transforming civil disobedience into a powerful tool for social change.