“The besieged had driven piles into the water before their old docks, that their vessels might be in safety behind them and the Athenians be unable to stand in amongst them and do any damage to the shipping.” The latter endeavoured to remove this species of nautical entrenchment, and for this purpose they constructed a raft on which were turrets and parapets to cover the men who embarked on it. It was towed up to a line of piles and used as a kind of covering battery for the crews of boats who removed the piles which had been “sawed off close to the bottom by divers.” A serious obstruction was offered by some piles driven in till their heads were below the surface of the water in the hope that the besieging ships might run upon it. But the divers, by persevering efforts, succeeded in sawing them through, thus enabling the besiegers to remove them. The Chronicles of the early Middle Ages supply instances of the employment of divers in naval warfare. The Baltic, we read, was so infested with pirates that a Swedish force was sent against them. The Swedish admiral, observing that the pirate vessels lay at anchor in a certain bay, sent in at night men from his own fleet to dive beneath them and make holes in their bottoms. The following day he engaged them. In the action the leaks made by the subaqueous assailants during the night proved so serious that the piratical crews had to turn their attention chiefly to stopping them and to baling out their vessels. The number available to fight their enemy was in consequence so reduced that the Swedes gained a complete victory and the power of the pirates was annihilated. Again at the siege of Malta by the Turks in the sixteenth century some furious under-water fighting occurred. The Maltese were excellent divers and the Knights took advantage of their skill to assist in the erection of a barricade across the mouth of one of the creeks which indent the shores of the Grand Harbour. This obstruction the Turkish besiegers endeavoured to remove, and accordingly they made upon it a series of determined attacks. The divers left their work to drive them off and a terrible and weird struggle ensued, frequently below the surface of the water, which finally ended in the repulse of the infidel assailants.