In a remarkable and wide-ranging interview with Thomas M. Cook of the New York Herald, Robert E. Lee identified the failure of the Constitution to settle “the question of defining the relative powers of the States, and their relation to the General Government” as giving rise to legitimate casus belli:
On the question of State sovereignty, the General contends that there exists a legitimate casus belli. In the convention that formed the organic law of the land, the question of defining the relative powers of the States, and their relation to the General Government, was raised, but after much discussion was dropped and unsettled. It has remained so unsettled until the present time. This war is destined to set it at rest. It was unfortunate that it was not settled at the outset; but as it was not settled then, and had to be settled at some time, the war raised on this issue cannot be considered treason. If the South is forced to submission in this contest, it of course can only be looked upon as the triumph of Federal power over State rights, and the forced annihilation of the latter.