William Henry Seward’s years in public life coincided with the struggle between northern and southern political leaders over the issue of slavery. The preservation of the Union and the growth of U.S. power abroad also became pressing concerns during this period. As both a public official and a partisan campaigner, Seward promoted the restriction of slavery and the strengthening of the United States as a nation built upon a free labor system. As secretary of state, he asserted America’s rights against foreign encroachment even as he faced the challenge of southern rebellion.