The necessity for keeping a keen look-out was early recognized. The Admiralty offered a reward not exceeding £1000 for information leading to the capture or destruction of an enemy vessel, including a mine-layer or submarine, and a sum up to £200 for information leading to the craft being sighted and chased. Prominent shipowners and other patriotic citizens aided and abetted these rewards by offering various sums to the captain and crew of the first British merchantman who sank a U-boat. In due course the idea of ‘camouflage’ was borrowed from the Army. In military campaigns the ingenious daubing of guns with paint that harmonized with the colours of the surrounding scenery became, if not high art, a most skilful artistic device. It was found impossible to make ships invisible at sea, but much was done to render them considerably less conspicuous. The constantly changing light defeated every plan that had invisibility for its aim. While it is a wise thing to consume one’s own smoke, steamers are unable to do so. Smoke is an excellent tell-tale. On the other hand it was not always a friend of the enemy. Destroyers in battle often put up a smoke-screen sufficiently dense to cover battleships and cruisers—it was a marked device of the German fleet at Jutland—and many a ‘black gang’ in the stokehold have saved their ship by its means. Boxes filled with smoke-making powder that burnt slowly and gave off black clouds when flung in the sea have enabled many a vessel to escape behind a dense pall. They played their part in the daring raids on Ostend and Zeebrugge. Special smoke-funnels for use on board were also introduced with success. The Compagnie Transatlantique liner _Le Gard_ escaped from two U-boats by means of this system. On those rare occasions when an unsuspecting U-boat popped up under the very nose of a patrol boat the lance-bomb proved a thoroughly efficient weapon. It consisted of a 14–lb. bomb that exploded on contact, placed on the end of a shaft some 6 feet in length. An expert thrower could hurl this naval hand-grenade quite a fair distance and with splendid precision. A destroyer or chaser towing explosive charges at breakneck speed was a sure and certain harbinger of death should a marauder happen to be in the way.