There is an impression at the North, in which we confess we have participated, that JEFFERSON DAVIS, the head of the pseudo Southern Confederacy is a man of extraordinary military ability. It is not good sense to underrate an opponent, nor is it right to overvalue him. To decide his exact proportions is the point of consequence. We scarcely know whence Mr. DAVIS derived his reputation as a general. Indeed, it is difficult to find anybody who does know. He behaved with great gallantry at Buena Vista; but that was mere bravery, not generalship. Beyond this, his reputation is the creature of report—one of the matter of courses which pass from mouth to mouth, emanating from friends and persons who are subject to be impressed by the great qualities which Mr. DAVIS does possess as a civilian. These reputations are commoner in the world than men generally are apt to think. JOHN C. BRECKINRIDGE, for instance, an oily, self-contained and handsome youth, who never did anything, except to look as pretty as possible, and to keep from positive action, has had an admiration and confidence from hosts of citizens, the reason of which none of them can tell. The instant he does anything positive, it is foolish and wicked, and above all, displays the fact that he neither knew the sentiment of his own State nor the extent of his personal influence. So we may say of JEFFERSON DAVIS as a general. He plunged into revolution when loyalty was slumbering. Before patriotism had taken the alarm he was consolidating his government, and with his co-conspirators, regarded secession as an established fact. The plottings of years had placed arms in his hands, and almost literally laid a great nation in the dust before treason, and gave traitors time, means, opportunity to stamp upon it and crush out its life. Yet, strange to say, with all these advantages, he is not even in a situation to select his own battle ground. The war is in the South and will stay there. This position is the result of a series of errors, which a great general—a man fit to found a nation—would never commit. He allowed the President to force him to the first blow at Fort Sumpter. Yet, the civilized world will agree that, even when the claim of independence was set up, months and years would elapse before it would be recognized, and that it was of the utmost importance that the sentiment opposed to the pseudo Confederacy should not be consolidated and made formidable by hostile collisions. So long as he could make the question a diplomatic one, patriotism would continue to slumber—doubts might remain in the minds of many honest people as to his ultimate designs—all material interests would have been occupied in efforts at peace,—and the government would have presented the appearance of inefficiency to foreign nations which would have induced the recognition of the sham Confederacy. These, to a great mind, are certainly enormous advantages; but Mr. DAVIS does not seem to have contemplated them. He gave way to the frenzy of his people, and struck the first blow at Charleston. We think this will be pronounced by history the great mistake of his rebellious career. But when it was done there opened to him certain necessities which he ought to have foreseen if he is so commanding a genius as he is represented to be. He should have taken Fort Pickens. With populations in North Carolina, Virginia and Maryland largely disaffected to the government, and ready to hail him as their deliverer and chief, and, above all, with Washington undefended, and the North unprepared, he should have marched upon and taken the capital. This would have fixed his Confederacy as a nation, and he would now, if he was a man of military energy, be at the head of the government de facto of the United States.

There are other advantages which have been lost by the Southern Confederacy, never to be regained, which evince a lack of foresight and an utter waste of opportunity upon the part of those in authority. JEFFERSON DAVIS is of course responsible. We do not doubt that his rebellion will go down to posterity not only as the most wicked, but in all military aspects as the worst conducted, the world ever witnessed. We are so firm in this conviction that we believe his subjugation and ignominious fall are now matters near us in the future. He has lost time to strike the bold, rapid blows which crown rebellion with success, and has given time for a free and loyal people to rise and crush him. His inefficiency is part of the destiny of the country. The constitution is not fated to sink. The loyal cohorts are now upon the move, and the people who have followed DAVIS in his treason will find him powerless to prevent their fields from being drenched with blood, their peace and wealth destroyed, and themselves subjugated and ruined.