FOR the next four months after March 21st, 1918, the enemy imposed his will by battle. He made five great attacks, in the first of which alone he used half his entire strength in the west. Thrice his tactics proved to be a master-key to unlock the great fortified system and to open the path to freedom of manœuvre. In extent of territory he won ten times more than the obliterated scraps wrested piecemeal by the Entente during the course of 1917. He advanced his line within forty miles of Paris. He took 225,000 prisoners and 2,500 guns, and inflicted nearly a million casualties. Yet this great achievement proved to be not merely a victory without a morrow, but one which had sown behind it the quick seeds of irremediable defeat. The initiative had scarcely dropped from Ludendorff's hand before Foch seized it, and in less than another four months Germany was thankfully accepting an armistice, scarcely distinguishable in its terms from a capitulation. The causes of this reversal of fortune--perhaps the swiftest and most dramatic in history--have, paradoxically enough, to be sought in the analysis of a series of striking successes. In fact, it was of momentous consequence for the Entente that the first blow was tactically so encouraging--had it been stopped dead, the Germans might in discouragement have reverted to defence. In that event their line, far shorter and straighter, and held by a far stronger and less exhausted garrison, would almost certainly have carried them in comparative safety through the campaigning season of the year. In 1919 it is improbable that defeat would have involved the terms dictated at Versailles, for a victory mainly achieved by American arms would have given President Wilson the power of imposing his 'Fourteen Points' in his own way.