But in 1863 the Government was incalculably strengthened by General Meade's victory at Gettysburg and by the opening of the Mississippi River to navigation in consequence of General Grant's capture of the rebel stronghold of Vicksburg.

The latter event practically destroyed the military power of the Rebellion on the western side of the Mississippi, and opened, as Mr.Lincoln hoped, a great opportunity for the formation of State governments loyal to the Union and able to aid effectively in the overthrow of the Rebellion.
To this end the President proposed a definite plan of reconstruction in his message of December 8, 1863, sent to the Thirty-eighth Congress at its first session.

He accompanied the message with a public proclamation which more fully embodied his conception of the necessities of the situation and the duties of the loyal people.
According to the message of the President "the constitutional obligation to guarantee to every State in the Union a Republican form of government and to protect the State in such cases is explicit and full.

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