222 TUF, rREDICAMEXT INCURRED CHAP, investment of the place — and this, be it always remembered, is the first indispensable step in the process of a regular siege — was a thing which could not be attempted, riieiost It may be said, and on sound authority, that a oi isolating" virtual investment of the place was at one time practicable; for if, in the month of September, the Allies had established a force on the great road which connected Sebastojiol with the north, they would have done much towards putting the fortress in a state of isolation ; and we have al- ready seen ground for believing that from such ?, measure the immediate fall of the place would have resulted ; * but this opportunity was for- feited by adopting the plan of the Hank march, and abandoning to the enemy, first the free en- joyment, and then the absolute and unchallenged dominion, of his great line of commimication between Sebastopol and the interior of Eussia. From the moment when the enemy — much doubt- ing at first, and slow to believe his good fortune — was suffered to make himself master on the Mackenzie Heights, the Allies were no longer able, except by a fresh invasion, to intercept the succour which henceforth, at the convenience of the Russians, could be freely poured into Sebas- topol. Before the flank march, the enterprise against Sebastopol was a swoop at rich prey, forming part, it is true, of a mighty empire, yet seated in an outlying province, and liable to be , torn off by force, if force could be used with due • 'Jnvasion of theCriraea,' vol. iii. of Cabinet Edition, chap, v.