Seward did his best to stop the southern states from seceding ; once that failed , he devoted himself wholeheartedly to the Union cause . His firm stance against foreign intervention in the Civil War helped deter the United Kingdom and France from possibly gaining the independence of the Confederate States . He was one of the targets of the 1865 assassination plot that killed Lincoln , and was seriously wounded by conspirator Lewis Powell . Seward remained in post through the presidency of Andrew Johnson , during which he negotiated the Alaska Purchase in 1867 and supported Johnson during his impeachment . His contemporary Carl Schurz described Seward as " one of those spirits who sometimes will go ahead of public opinion instead of tamely following its footprints "
assassination plot
Assassination of Abraham Lincoln
William H. Seward