Historical leader Henry David Thoreau is known for his philosophy of civil disobedience, which he articulated in his essay of the same name. Thoreau advocated for nonviolent resistance against unjust government actions, particularly regarding issues like slavery and the Mexican-American War. His thoughts on individual conscience and moral responsibility have had a lasting impact on political movements, influencing figures such as Martin Luther King Jr. and Mahatma Gandhi. Thoreau's emphasis on personal ethics remains relevant in discussions surrounding social justice and activism.