Which American Secretary of War later became President of the Confederate States?

The correct response is Jefferson Davis, who served as the Secretary of War under President Franklin Pierce before becoming the President of the Confederate States during the American Civil War. His tenure as Secretary of War from 1853 to 1857 provided him with significant military and governmental experience, which he later utilized when he took on the leadership role of the Confederacy. After the secession of several Southern states, Davis was elected as the President of the Confederate States in 1861, a position he held until the Confederacy's defeat in 1865. His background in military and political affairs allowed him to navigate the challenges faced by the Confederacy, although his leadership came with various controversies and criticisms.

The other choices are historical figures, but they do not fit the description of having held the position of Secretary of War before becoming a president of the Confederate States. Henry Clay was a prominent political figure but was never Secretary of War or President. William Seward was Secretary of State and played a key role in the Lincoln administration. Franklin Pierce was a president himself before the Civil War but did not lead the Confederacy or serve as a Secretary of War in the context of the Confederate States.