Here, for example, was a ship at New York, all loaded and ready to sail for the war zone. The master visited the port officer at the British consulate, who directed him to proceed to Gravesend Bay, anchor his vessel, and report to the convoy officers for further instructions. The merchant captain, reaching this indicated spot, usually found several other vessels on hand, all of them, like his ship, waiting for the sailing date. The commander of the gathering convoy, under whose instructions all the merchantmen were to operate, was a naval officer, usually of the rank of commodore or captain, who maintained constant cable communication with the convoy room of the Admiralty and usually used one of the commercial vessels as his flagship. When the sailing day arrived usually from twenty to thirty merchantmen had assembled; the commander summoned all their masters, gave each a blue book containing instructions for the management of convoyed ships, and frequently delivered something in the nature of a lecture. Before the aggregation sailed it was joined by a cruiser or pre-dreadnought battleship of the American navy, or by a British or French cruiser. This ship was to accompany the convoy across the Atlantic as far as the danger zone; its mission was not, as most people mistakenly believed, to protect the convoy from submarines, but to protect it from any surface German raider that might have escaped into the high seas. The Allied navies constantly had before their minds the exploits of the _Emden_; the opportunity to break up a convoy in mid-ocean by dare-devil enterprises of this kind was so tempting that it seemed altogether likely that Germany might take advantage of it. To send twenty or thirty merchant ships across the Atlantic with no protection against such assaults would have been to invite a possible disaster. As a matter of fact, the last German raider that even attempted to gain the high seas was sunk in the North Sea by the British Patrol Squadron in February, 1917.