After the war was fairly begun, the British mercantile shipping always sailed either under convoy or as armed “running ships” that did not wait for the slow and comparatively rare opportunities of convoy, but trusted to their guns for defence. The new American privateer was adapted to meet both chances. Two or three such craft hanging about a convoy could commonly cut off some merchantman, no matter how careful the convoying man-of-war might be. By night they could run directly into the fleet and cut out vessels without even giving an alarm, and by day they could pick up any craft that lagged behind or happened to stray too far away. Yet the “running ships” were the chief objects of their search, for these were the richest prizes; and the capture of a single such vessel, if it reached an American port in safety, insured success to the cruise. The loss of these vessels caused peculiar annoyance to the British, for they sometimes carried considerable amounts of specie, and usually were charged with a mail which was always sunk and lost in case of capture. As the war continued, experience taught the owners of privateers the same lesson that was taught to the government. The most efficient vessel of war corresponded in size with the “Hornet” or the new sloops-of-war building in 1813. Tonnage was so arbitrary a mode of measurement that little could be learned from the dimensions of five hundred tons commonly given for these vessels; but in a general way they might be regarded as about one hundred and fifteen or one hundred and twenty feet long on the spar-deck and thirty-one feet in extreme breadth. Unless such vessels were swift sailers, particularly handy in working to windward, they were worse than useless; and for that reason the utmost effort was made both by the public and private constructors to obtain speed. At the close of the war the most efficient vessel afloat was probably the American sloop-of-war, or privateer, of four or five hundred tons, rigged as a ship or brig, and carrying one hundred and fifty or sixty men, with a battery varying according to the ideas of the captain and owners, but in the case of privateers almost invariably including one “long Tom,” or pivot-gun. Yet for privateering purposes the smaller craft competed closely with the larger. For ordinary service no vessel could do more effective work in a more economical way than was done by Joshua Barney’s “Rossie” of Baltimore, or Boyle’s “Comet” of the same port, or Champlin’s “General Armstrong” of New York,--schooners or brigs of two or three hundred tons, uncomfortable to their officers and crews, but most dangerous enemies to merchantmen. Vessels of this class came into favor long before the war, because of their speed, quickness in handling, and economy during the experience of twenty years in blockade-running and evasion of cruisers. Such schooners could be built in any Northern sea-port in six weeks or two months at half the cost of a government cruiser.