ON Saturday, 31st August, Major-General Fremont, commanding at St. Louis, Missouri, issued a proclamation placing the whole State of Missouri under martial law, and further stating :

"All persons who shall be taken with arms in their hands within these lines shall be tried by court-martial, and, if found guilty, will be shot. The property, real and personal, of all persons in the State of Missouri who shall take up arms against the United States, and who shall be directly proven to have taken active part with their enemies in the field, is declared to be confiscated to the public use; and their slaves, if any they have, are hereby declared free."

It has been stated by some of the papers that in thus pronouncing the emancipation of the slaves of rebels General Fremont was only carrying out the Act known as the Confiscating Act passed by Congress at the extra Session. An examination of that act will, however, show that its provisions do not warrant the step taken by the General. The only section in which any reference is made to slaves is the following :

SEC. 4. And be it further enacted, That whenever hereafter, during the present insurrection against the Government of the United States, any person claimed to be held to labor or service under the law of any State shall be required or permitted by the person to whom such labor or service is claimed to be due, or by the lawful agent of such person, to take up arms against the United States; or shall be required or permitted by the person to whom such labor or service is claimed to be due, or his lawful agent, to work or to be employed in or upon any fort, navy-yard, dock, armory, ship, intrenchment, or in any military or naval service whatsoever, against the Government and lawful authority of the United States, then, and in every such case, the person to whom such labor or service is claimed to be due shall forfeit his claim to such labor, any law of the State or of the United States to the contrary notwithstanding. And whenever thereafter the person claiming such labor or service shall seek to enforce his claim, it shall be a full and sufficient answer to such claim that the person whose service or labor is claimed had been employed in hostile service against the Government of the United States, contrary to the provisions of this act.

It thus appears that the only slaves who can be forfeited under this Act are those who have been " employed in hostile service against the United States Government;" whereas Major-General Fremont's proclamation grants freedom to the slaves of every rebel, whether they have been employed in military service or not. The General, therefore, has evidently based his action, not upon the law of Congress, but upon something else.

That something else is THE WAR POWER, which is inherent in the Government, and is exercised by its delegated officers commanding the forces of the United States. What the nature of this war power is, and what it may do with slavery, may be gathered from the following extract from a speech delivered by ex-President John Q. Adams, in the House of Representatives, on April 14, 1842 :

When your country is actually in war. whether it be a war of invasion or a war of insurrection, Congress has power to carry on the war, and must carry it on according to the laws of war, and by the laws of war an invaded country has all its laws and municipal institutions swept by the board, and martial law takes the place of them. This power in Congress has perhaps never been called into exercise under the present Constitution of the United States. But when the laws of war are in force, what, I ask, is one of those laws? It is this, that when a country is invaded, and two hostile armies are set in martial array, the commanders of both armies have power to emancipate all the slaves in the invaded territory. Nor is this it mere theoretic statement. The history of South America shows that the doctrine has been carried into execution within the last thirty years. Slavery was abolished in Columbia, first by the Spanish General Morillo, and secondly by the American General Bolivar. It was abolished by virtue of a military command given at the head of the army, and its abolition continues to be law to this day. It was abolished by the laws of war, and not by municipal enactments. I might furnish a thousand proofs to show that the pretensions of gentlemen to the sanctity of their municipal institutions, under a state of actual invasion and of actual war, whether servile, civil, or foreign, are wholly unfounded, and that the laws of war do, in all such cases, take the precedence. I lay this down as the law of nations. I say that the military authority takes, for the time, the place of all municipal institutions, slavery among the rest. Under that state of things, so far from its being true that the States where slavery exists have the exclusive management of the subject, not only the President of the United States, but the commander of the army, has power to order the universal emancipation of the slaves.

John Quincy Adams thus held that, whenever a war grew out of slavery, martial law might be proclaimed in any part of the Union, and that such proclamation " swept by the board" all municipal and local laws establishing or recognizing slavery. It may seem superfluous to quote authorities in support of the assertions of so sound a jurist as Mr. Adams. We may mention, however, that he merely repeats, in the speech above quoted, the views of the recognized expounders of the common law. Sir Matthew Hale (Hist. C. L. c. 2), says that martial lacy is built upon no settled principles, but is entirely arbitrary in its decisions; it is in truth and reality no law, but something rather indulged than allowed as a law." Blackstone quotes this passage (Comm., I. 413) and emphatically approves it ; adding that in time of war court-martials have " almost an absolute legislative power." Modern jurists confirm these views, and admit that in actual warfare the powers of the general commanding are dictatorial.

We run no risk, therefore, in stating that, in decreeing the emancipation of the slaves owned by rebels in the State of Missouri, General Fremont has neither, on the one hand, relied upon the recent Act of Congress relating to confiscation, nor, on the other, exceeded the proper limits of his authority as General commanding. Under his proclamation of martial law, all state and municipal laws were at once suspended, and he, as commanding General, was practically invested with dictatorial powers over persons and property, for the just use of which powers he tacitly undertook to render account when martial law ceased to exist in his Department.

The direct consequences of his decree, so far as slavery in Missouri is concerned, can not be of much importance. Missouri does not contain 125,000 slaves, and of these considerably more than one half are believed to be held by loyal men. Moreover, under the terms of Fremont's proclamation, no slave can be emancipated until it is proved that his owner has been actually in arms, or laboring actively in aid of those who are in arms against the Government: a large number of slaves may thus be defrauded of emancipation through the want of evidence to establish the treason of their masters. It is doubtful whether 25,000 human beings will exchange slavery for freedom under the proclamation of General Fremont.

But its moral effect must be signal. It is a solemn warning to the inhabitants of the rebel States, that wherever the armies of the United States are resisted in the interests of slavery, the cause of the resistance will be removed. It is a pregnant hint that the rebels who have falsely accused us of being abolitionists may, if they choose, make their accusation true. It is a notification to Kentucky, which seems to be on the eve of explosion, that open treason will necessarily involve the extirpation of slavery. This rebellion has more than once recalled the old adage, " Those whom the Gods wish to destroy they first render mad :" we shall now see how far the madness extends. The cost of rebellion is abolition. Those who choose may purchase.

Another important result of General Fremont's proclamation has been the discovery of the fact that the people of the North are much more solidly united on the question of slavery than was imagined. It had been generally supposed that the first utterance of the cry of emancipation would divide the North into two hostile camps. How this strange delusion came to be entertained it is difficult to discover; the least reflection should have satisfied every one that it was impossible to build up at the North a party based on protection to slavery any where. But, however the notion originated, there is no doubt it did exist, and that leading men and journals in the confidence of the Administration were so thoroughly imbued with it, that they indignantly repudiated the imputation of being friendly to freedom under any circumstances. It seems, from the temper in which the public receive General Fremont's proclamation, that they are not so tender on the subject. They seem very well satisfied with the prospect. We hear no complaints, no lamentations over the downfall of slavery in Missouri. The respectable Democrats of this part of the country express themselves rather pleased than otherwise. Of course, it must be expected that the lottery-policy dealers and the profligate vagabonds who pretend to represent the Democracy in convention will testify their sorrow at the event, as they will do at every success of the National arms: but neither in this nor in any other particular do they express the sense of the rank and file of the Democracy.

What people want now is decided, startling, effective successes on the part of the United States. If these are achieved, no one will complain of what they may cost. Our Generals may emancipate every slave in the country, and lay waste every field from the Potomac to the Rio Grande-the people will sustain them, provided they crush out the enemy and restore the supremacy of the Government. But there will be no mercy for the general who, for fear of breaking a law or dividing a party, suffers the rebels to progress from victory to victory, and the Stars and Stripes to endure defeat after defeat, and disgrace after disgrace.