It may be said that although the authority to exercise exclusive legislation in certain cases within the States with their consent may be considered as a prohibition to Congress to exercise like exclusive legislation in any other case, although their consent should be granted, it does not prohibit the exercise of such jurisdiction or power within a State as would be competent to all the purposes of internal improvement. I can conceive no ground on which the idea of such a power over any part of the territory of a State can be inferred from the power to declare war. There never can be an occasion for jurisdiction for military purposes except in fortifications, dockyards, and the like places. If the soldiers are in the field or are quartered in garrisons without the fortifications, the civil authority must prevail where they are. The government of the troops by martial law is not affected by it. In war, when the forces are increased and the movement is on a greater scale, consequences follow which are inseparable from the exigencies of the state. More freedom of action and a wider range of power in the military commanders, to be exercised on their own responsibility, may be necessary to the public safety; but even here the civil authority of the State never ceases to operate. It is also exclusive for all civil purposes. Whether any power short of that stated would be adequate to the purposes of internal improvement is denied. In the case of territory one government must prevail for all the purposes intended by the grant. The jurisdiction of the United States might be modified in such manner as to admit that of the State in all cases and for all purposes not necessary to the execution of the proposed power; but the right of the General Government must be complete for all the purposes above stated. It must extend to the seizure and condemnation of the property, if necessary; to the punishment of offenders for injuries to the roads and canals; to the establishment and enforcement of tolls, etc. It must be a complete right to the extent above stated or it will be of no avail. That right does not exist.