The next object of inquiry is whether the right to declare war includes the right to adopt and execute this system of improvement. The objections to it are, I presume, not less conclusive than those which are applicable to the grant which we have just examined.

Under the last-mentioned grant a claim has been set up to as much of that system as relates to roads. Under this it extends alike to roads and canals.

We must examine this grant by the same rules of construction that were applied to the preceding one. The object was to take this power from the individual States and to vest it in the General Government. This has been done in clear and explicit terms, first by granting the power to Congress, and secondly by prohibiting the exercise of it by the States. "Congress shall have a right to declare war." This is the language of the grant. If the right to adopt and execute this system of improvement is included in it, it must be by way of incident only, since there is nothing in the grant itself which bears any relation to roads and canals. The following considerations, it is presumed, prove incontestably that this power has not been granted in that or any other manner.

The United States are exposed to invasion through the whole extent of their Atlantic coast by any European power with whom we might be engaged in war—on the northern and northwestern frontier on the side of Canada by Great Britain, and on the southern by Spain or any power in alliance with her. If internal improvements are to be carried to the full extent to which they may be useful for military purposes, the power as it exists must apply to all the roads of the Union, there being no limitation to it. Wherever such improvements may facilitate the march of troops, the transportation of cannon, or otherwise aid the operations or mitigate the calamities of war along the coast or in any part of the interior they would be useful for military purposes, and might therefore be made. The power following as an incident to another power can be measured as to its extent by reference only to the obvious extent of the power to which it is incidental. So great a scope was, it is believed, never given to incidental power.

If it had been intended that the right to declare war should include all the powers necessary to maintain war, it would follow that nothing would have been done to impair the right or to restrain Congress from the exercise of any power which the exigencies of war might require. The nature and extent of this exigency would mark the extent of the power granted, which should always be construed liberally, so as to be adequate to the end. A right to raise money by taxes, duties, excises, and by loan, to raise and support armies and a navy, to provide for calling forth, arming, disciplining, and governing the militia when in the service of the United States, establishing fortifications and governing the troops stationed in them independently of the State authorities, and to perform many other acts is indispensable to the maintenance of war—no war with any great power can be prosecuted with success without the command of the resources of the Union in all these respects. These powers, then, would of necessity and by common consent have fallen within the right to declare war had it been intended to convey by way of incident to that right the necessary powers to maintain war. But these powers have all been granted specifically with many others, in great detail, which experience had shown were necessary for the purposes of war. By specifically granting, then, these powers it is manifest that every power was thus granted which it was intended to grant for military purposes, and that it was also intended that no important power should be included in this grant by way of incident, however useful it might be for some of the purposes of the grant.

By the sixteenth of the enumerated powers, Article I, section 8, Congress are authorized to exercise exclusive legislation in all cases whatever over such district as may by cession of particular States and the acceptance of Congress, not exceeding 10 miles square, become the seat of the Government of the United States, and to exercise like authority over all places purchased by the consent of the legislature of the State in which the same shall be, for the erection of forts, magazines, arsenals, dockyards, and other useful buildings. If any doubt existed on a view of other parts of the Constitution respecting the decision which ought to be formed on the question under consideration, I should suppose that this clause would completely remove it. It has been shown after the most liberal construction of all the enumerated powers of the General Government that the territory within the limits of the respective States belonged to them; that the United States had no right under the powers granted to them, with the exception specified in this grant, to any the smallest portion of territory within a State, all those powers operating on a different principle and having their full effect without impairing in the slightest degree this right in the States; that those powers were in every instance means to ends, which being accomplished left the subject—that is, the property, in which light only land could be regarded—where it was before, under the jurisdiction and subject to the laws of the State governments.

The second number of the clause, which is applicable to military and naval purposes alone, claims particular attention here. It fully confirms the view taken of the other enumerated powers, for had it been intended to include in the right to declare war, by way of incident, any right of jurisdiction or legislation over territory within a State, it would have been done as to fortifications, magazines, arsenals, dockyards, and other needful buildings. By specifically granting the right as to such small portions of territory as might be necessary for these purposes and on certain conditions, minutely and well defined, it is manifest that it was not intended to grant it as to any other portion on any condition for any purpose or in any manner whatsoever.

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.

The reasons which operate in favor of the right of exclusive legislation in forts, dockyards, etc., do not apply to any other places. The safety of such works and of the cities which they are intended to defend, and even of whole communities, may sometimes depend on it. If spies are admitted within them in time of war, they might communicate intelligence to the enemy which might be fatal. All nations surround such works with high walls and keep their gates shut. Even here, however, three important conditions are indispensable to such exclusive legislation: First, the ground must be requisite for and be applied to those purposes; second, it must be purchased; third, it must be purchased by the consent of the State in which it may be. When we find that so much care has been taken to protect the sovereignty of the States over the territory within their respective limits, admitting that of the United States over such small portions and for such special and important purposes only, the conclusion is irresistible not only that the power necessary for internal improvements has not been granted, but that it has been clearly prohibited.