The navy that invested the harbor entertained no illusions on that score. It had not dared the attempt to force the passages of Narragansett. It would not dare to force the passages of Boston. As at Narragansett, its business was to occupy the defenders and wear them out while the army fell on them and on Boston from the land.[92] [Illustration: MAP ILLUSTRATING THE ENEMY ATTACK ON BOSTON AND NEIGHBORING CITIES] _The Deadly Blind Man’s Buff_ The ships entered a shrouded, black sea where there was not a light to warn of reef or shoal. Lightless themselves, they groped with deep-sea leads and sounding machines till they assured themselves of safe positions where they might have sea-room to swing around in great closed circles at high speed. These circles would cut deeply into the circles of the fire zones of the defenses. At close range the vessels, invisible to the forts, could send a furious volley into them, and rush past before the guns could find them, to return on their circle and fire from some other point. It was the penalty that darkness lays on land defenses. But it penalized the ships, also.[93] They would have to fire without sighting their mark. They dared not betray themselves to the waiting guns on land by throwing their search-lights on the defenses, while the defenses could sweep the sea incessantly, for their searchlights were disposed along miles of coast, far aloof from the batteries. If the search-lights were effective, the ships should have to flee to the farthest limit of the coast guns’ range. At that distance they, in turn, could not deliver an effective bombardment of the land so long as it was dark. So, then, all the ferocious game of war centered for the time on the search-lights. The death-laden ships, the death-laden guns on land, had to wait till it was learned what the lights would do.[94] The enemy knew that the American defenses had only about one-half the search-light installation that was needed. The hostile sailors had not been forced to depend on spies for this information. It was in American reports that had been made to Congress session after session.[95] They had prepared for their game of blind man’s buff by long consultations over charts. Every ship’s officer was provided with minute instructions for every contingency that human wit could forecast in the headlong game of chess that is played with cannon. _Defenders Stand Prepared_ The defenders were ready, too. In the human chain that began with the battle commander, and reached from him through links of district commanders to fire commanders and battery commanders, each man had his orders for any one of a hundred things that might occur, however quickly it might come.