Historians argue that Secretary of State William H. Seward abandoned the pursuit of his expansionist vision during the Civil War. They interpret his conduct of wartime
Mexican policy as a case in point for this argument. Although Seward wished to see the Mexican republic stabilised and eventually incorporated into the United States, he allegedly remained neutral towards the French invasion of Mexico 1862-67 in order to prevent Emperor Napoleon III from striking up an alliance with the Confederacy.
This thesis argues that Seward never gave up expansionism and that his wartime Mexican policy was designed to facilitate the future absorption of that country into the U.S. republic. Seward believed the Civil War signalled the coming demise of slavery, which had complicated previous instances of national territorial growth, in the United States. He also saw the French invasion of Mexico as an opportunity for the Mexicans
to prove their commitment to republicanism and therefore their readiness to become citizens of the U.S. republic. Once both these crises had passed, Seward predicted, the next stages of U.S. expansionism – the peaceful incorporation of Mexico into the United States – would follow. As secretary of state, Seward used his influence over Mexican policy to facilitate the realisation of this goal.
This thesis tracks the development of Seward’s pre-war expansionist outlook and compares it to his approach to wartime relations with Mexico, an undertaking not yet attempted by historians. During the antebellum era Seward advocated a method for expansion whereby the United States would build relations based on non-intervention, ideological affinity, and commercial cooperation with those countries it wished to absorb. These same principles guided and shaped Seward’s Mexican policy and his response to the French invasion in 1862. In regards to Mexico, Seward made significant advances towards furthering his expansionist ambitions during the Civil War
