James Madison is known for being which of the following?

James Madison is recognized as the "Father of the Constitution" primarily due to his pivotal role in the drafting of the U.S. Constitution and his advocacy for its ratification. Madison's contributions included his authorship of the Virginia Plan, which proposed a strong national government and served as a blueprint for the Constitution's structure. He was also instrumental in the formulation of the Bill of Rights, ensuring that individual liberties were protected. His deep understanding of political theory and his writings in the Federalist Papers further solidified his status as a foundational figure in American constitutional design.

The other options represent different historical figures or roles that do not align with Madison's contributions. The first Secretary of State was Thomas Jefferson, and the Civil Rights Movement was led by figures such as Martin Luther King Jr. Additionally, while the Commander-in-Chief of the Armed Forces is a role held by the President, Madison's primary legacy lies in his influence on the Constitution rather than military leadership. Overall, Madison’s achievements in constitutional development uniquely position him as a central architect of American government.