The President's right to proclaim the slaves free, as a war measure, was questioned not only by his violent political opponents, but also by a considerable number who were friendly to him, or at least to the cause of the Union, but whose knowledge of international law and war powers was limited. Among these were Congressman Crittenden and Wickliffe, of Kentucky, who were stanch supporters of the Union, and Mr. Wickliffe offered resolutions declaring that the President has no right whatever to interfere with slavery even during a rebellion. The whole subject was treated in a masterly way by the Hon. William Whiting in his book entitled "War Powers under the Constitution of the United States." He says: "The liberation of slaves is looked upon as a means of embarrassing or weakening the enemy, or of strengthening the military power of our army. If slaves be treated as contraband of war, on the ground that they may be used by their masters to aid in prosecuting war, as employees upon military works, {191} or as laborers furnishing by their industry the means of carrying on hostilities; or if they be treated as, in law, belligerents, following the legal condition of their owners; or if they be deemed loyal subjects having a just claim upon the Government to be released from their obligations to give aid and service to disloyal and belligerent masters, in order that they may be free to perform their higher duty of allegiance and loyalty to the United States; or if they be regarded as subjects of the United States, liable to do military duty; or if they be made citizens of the United States, and soldiers; or if the authority of the masters over their slaves is the means of aiding and comforting the enemy, or of throwing impediments in the way of the Government, or depriving it of such aid and assistance, in successful prosecution of the war, as slaves would and could afford if released from the control of the enemy; or if releasing the slaves would embarrass the enemy, and make it more difficult for them to collect and maintain large armies; in either of these cases, the taking away of these slaves from the 'aid and service' of the enemy, and putting them to the aid and service of the United States, is justifiable as an act of war. The ordinary way of depriving the enemy of slaves is by declaring emancipation."