Henry David Thoreau is the historically significant figure associated with the philosophical underpinnings of civil disobedience. His essay, "Civil Disobedience," published in 1849, articulated the moral imperative to resist unjust laws and governmental actions. Thoreau argued that individuals should prioritize their conscience over compliance with government mandates, especially in the context of slavery and the Mexican-American War. His ideas inspired future civil rights leaders, including Martin Luther King Jr. and Mahatma Gandhi, who embraced nonviolent resistance rooted in individual moral conviction. Thoreau's emphasis on personal integrity and social responsibility continues to resonate within contemporary social justice movements.