The impression was spread abroad that the crossing was to be effected by stealth, in calm, fog, or the darkness of a long winter night, without the protection of a fleet. Almost from the first, however, Bonaparte seems to have had no such intention. The armament of the flotilla itself proved of slight value, and he was resolved to take no uncalled-for risks, on an unfamiliar element, with 100,000 men. An essential condition, which greatly complicated the whole undertaking, became the concentration of naval forces in the Channel sufficient to secure temporary control. "Let us be masters of the Strait for 6 hours," Napoleon wrote to Latouche-Treville in command of the Toulon fleet, "and we shall be masters of the world." In less rhetorical moments he extended the necessary period to from two to fifteen days.
Up to the spring of 1804 neither army nor flotilla was fully ready, and thereafter the crossing was always definitely conditioned upon a naval concentration. But the whole plan called for swift execution. As time lapsed, difficulties multiplied. Harbors silted up, transports were wrecked by storms, British defense measures on land and sea grew more formidable, the Continental situation became more threatening. The Boulogne army thus became more and more--what Napoleon perhaps falsely declared later it had always been--an army concentrated against Austria. To get a fleet into the Channel without a battle was almost impossible, and once in, its position would be dangerous in the extreme. Towards the end, in the opinion of the French student Colonel Desbrière, Napoleon's chief motive in pressing for fleet coöperation was the belief that it would lead to a decisive naval action which, though a defeat, would shift from his own head the odium of failure.
Whether this theory is fully accepted or not, the fact remains that the only sure way of conquering England was by a naval contest. Her first and main defense was the British fleet, which, spread out to the limits of safety to watch French ships wherever harbored, guarded not only against a concentration in the Channel, but against incursions into other fields. The immediate defense of the coasts was intrusted to flotillas of armed boats, over 700 in all, distributed along the coast from Leith south-about to Glasgow, with 100 on the coast of Ireland. Naval men looked upon these as of slight value, a concession, according to Earl St. Vincent, to "the old women in and out" (of both sexes) at home. The distribution of the main battle squadrons varied, but in March, 1805, at the opening of the Trafalgar campaign they were stationed as follows: Boulogne and the Dutch forces were watched by Admiral Keith with 11 of the line and 150 smaller units scattered from the Texel to the Channel Islands. The 21 French ships under Ganteaume at Brest, the strategic center, were closely blockaded by Cornwallis, whose force, by Admiralty orders, was not to fall below 18 of the line. A small squadron had been watching Missiessy's 5 ships at Rochefort and upon his escape in January had followed him to the West Indies. The 5 French and 10 Spanish at Ferrol and the 6 or more ready for sea at Cadiz were held in check by forces barely adequate. In the Gulf of Lyons Nelson with 13 ships had since May, 1803, stood outside the distant but dangerous station of Toulon. Owing to the remoteness from bases, a close and constant blockade was here impossible; moreover, it was the policy to let the enemy get out in the hope of bringing him to action at sea.