At the same time the invaders adopted the additional plan of blockading the mountains both by sea and land. Besides the line of fortresses commenced by Peter the Great on the Terek, extended by Catherine westward, and now completed from sea to sea, similar establishments were created on all the points of the Black Sea coast which could conveniently be approached by water. Under pretence of carrying out a rigid system of quarantine regulations and tariff laws, the object was to cut off the Circassians from all foreign intercourse, and especially from trade with the Turks, who were in the habit of supplying them with arms, gunpowder, salt, and various necessary articles of manufacture. At the same time, the Russians endeavored by making certain marts of their own free to the mountaineers, to induce them gradually to exchange the habits of war for those of trade and friendly intercourse with their adversaries. Emissaries were sent among the tribes to attempt to win them over to this change of policy; rank in the army was offered to the chiefs; or they were tempted by pensions; and even by the introduction of foreign brandy as well as foreign gold, efforts were made to spread the fatal net of Russian influence along all the footpaths of freedom in the mountains. The Circassians liked the taste of the foreign liquor, and their eyes were not insensible to the charms of coined gold, of which they had before seen but little. The epaulettes also and stars and ribands were such baubles as were well adapted to captivate the fancy of semi-civilized chieftains; and the Russian fabrics were a temptation to all, especially to the women; but to the honor of the Circassians, the tribes with few exceptions disdained to sell their birthright of independence for a mere mess of pottage. Relations of trade and amity could be established only with the tribes whose position on the frontier compelled them to be neutral. The chiefs in the interior, though often jealous of each other, held themselves too high to be bought by the common enemy for a price; and the intrigue of the czar was on the whole as unsuccessful as his arms. The Circassians at first made little or no change in their mode of warfare to meet the new tactics of the invader. Still despising the men who dwelt in plains notwithstanding their cannon "made the earth to tremble and the fruit drop from the trees," they continued from time to time to storm the kreposts sabre in hand. They leaped out of their places of ambush upon the columns which attempted to penetrate into their fastnesses; and attacking the more numerous enemy in dense masses as formerly practised by the Turkish spahis, setting all modern tactics at defiance, and bent on bearing down every thing before them by the mad fury of their onset, they rushed upon the Russian squares and guns as if they had been the mere branches of trees used in their own mock-fights.