Welles supported President Johnson in his quarrel with Congress, took part in the Liberal Republican movement of 1872, and returning to the Democratic party, warmly advocated the election of Samuel J.
In the following year he became involved in the deadly quarrel between President Johnson and Congress.
At the close of the war he was appointed by President Johnson secretary of Montana Territory, and there, in the absence of the territorial governor, he acted as governor from September 1866 until his death from accidental drowning in the Missouri River near Fort Benton, Montana, on the 1st of July 1867.
Seward gradually regained his health, and remained in the cabinet of President Johnson until the expiration of his term in 1869.
To tie the president's hands Congress had passed the Tenure of Office Act, forbidding the president to remove any cabinet officer without the consent of the Senate; but in August 1867 President Johnson suspended Secretary Stanton and appointed Grant secretary of war ad interim until the pleasure of the Senate should be ascertained.