There is only one answer to that. It is for defenders on land to plant huge guns far inland that can reach the ships and beat them back that they dare not come close enough to reach the lesser shore artillery nearer the sea. This formula of shore-defense is a formula so simple that a mathematician, given the conditions, can work it out with simple arithmetic though he never had seen a cannon in his life. Guns, guns, and again guns--and an army to protect them! This was the only possible reply to the fleet that was pounding the coast. The United States had not enough sufficiently powerful mobile coast guns and siege guns. It had not enough artillerists to fight what guns there were. And it had not enough ammunition to provide them with food.[28] In Bethlehem, Pennsylvania; up the Hudson, in smoky Watervliet; in Hartford and Bridgeport and New Haven, and a dozen other towns, with machinery hastily assembled, and workmen hastily learning, they were trying, now, to make projectiles enough, and guns enough. They were trying to make enough powder, down in Delaware and New Jersey. In the encampment of the United States army at that moment trains were delivering guns--guns made in record time, magnificent testimony to American efficiency under stress. But the guns were coming in one by one--to meet an enemy who was beating at the gates and could not be stopped except with hundreds. _The Enemy on the Mainland!_ Even then the flag-ship off the coast was sputtering a code into the night. It was a long code, but its meaning was short. It meant: “Now!” The mine-sweepers hauled their gear and came out. Fourteen had gone in. Those that came out were nine. Before they had well begun to move, the beach was white with ships’ boats, and nine hundred bluejackets and marines set foot on the mainland of the United States.[29] With sharpened knives in their sheaths, and loaded carbines, and bandoleers filled with cartridges, and entrenching tools and provisions, each man of that first force presented the highest attainable unit-efficiency for war. The boats were scarcely off the beach, to return to the ships, before eight hundred of these units were trotting through the up-land, throwing out advance parties, and making hasty trenches from which, in a moment, there looked the greyhound muzzles of machine-guns. On the shore, the strand-party was sinking sand-anchors and rigging derricks. Others were setting together the five and one-half foot sections of jointed hollow masts for the wireless. When the boats beached again, with more men, two 40-foot masts reached into the night, and hand-power generators were making the antennæ pulse with their mysterious life.