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 recognizing 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 his 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".