William H. Seward was an American politician and statesman who served as the Secretary of State under Presidents Abraham Lincoln and Andrew Johnson. He is best known for his role in the purchase of Alaska from Russia in 1867, a deal often referred to as "Seward's Folly" at the time, which later proved to be a significant expansion of U.S. territory. Seward was also a prominent figure in the Republican Party and a strong opponent of the expansion of slavery in the United States. He played a key role in shaping foreign policy during the Civil War and was influential in promoting the idea of American exceptionalism.