As in the adoption of those deadly hand-grenades, which played so important a part in all the battles of the siege, so in the construction of parallels and the tunnelling of mines the world saw a return to the practice and methods of the 17th century. To find a counterpart to these huge forts of Port Arthur, with their scarps and counter-scarps, their glacis and cuponniéres and ravelins, one has to go back to the system of the great military engineer Vanban, who carried the science of fortification to its highest perfection. There was only one assailant to which these mighty works were not impregnable--and that assailant was the explosive power of dynamite. This resistless auxiliary the Japanese made speed to enlist in their service. [Sidenote: The Russian Fleet between Two Fires] Meanwhile, leaving the sappers to their insidious task on the east, the Japanese artillerists were swift to take advantage of the new position won for them on the west. From the summit of 203 Metre Hill, the whole town and harbor of Port Arthur lay revealed, and the remnant of the Russian fleet which lay sheltered there could no longer escape the searching attentions of the Japanese shells. The great howitzers, firing their 500 lb. projectiles, and the big naval guns were quickly moved into position, and, directed from the observation station on 203 Metre Hill, they began to drop shot after shot on the helpless men-of-war. So perfect was the command, that it was possible for the besiegers to count every day the hits they made, and to specify the particular ships against which they had been recorded. One after another these mighty vessels succumbed to the incessant pounding that they received, and in a few days the four battleships _Retvisan_, _Peresviet_, _Pobieda_ and _Poltava_, and the armored cruiser _Bayan_ were reported sunk or damaged so as to be unseaworthy. Only the _Sevastopol_ remained, and she temporarily escaped to the outer roadstead, with consequences that will be related presently. These ships were the real objective of the siege. Their disablement preserved Japan from her most serious menace; but next to that consummation, their capture was a point of primary importance. The Japanese naturally desired not only to render these powerful vessels useless to their adversaries, but to make them useful to themselves. Accordingly, having made sure that the ships were injured beyond the power of the Port Arthur docks to repair them, the besiegers were careful to inflict no further damage on them. By the 12th the Japanese gunners had attained their object, and the _Sevastopol_ was the only seaworthy survivor of the Russian squadron; and attention was forthwith turned to her from another direction. Admiral Togo, whose fleet had been cruising outside Port Arthur to shut off the natural avenue of escape for the wretched Russian fleet, now directed his torpedo-boats to attack the battleship _Sevastopol_ as she lay at her moorings in the outer roadstead. Her