only a torpedo boat of larger size. But the early torpedo was subject to some disadvantages. It could not be used with effect at more than 2,000 yards. Water resistance rendered its course uncertain and comparatively slow, so that a moving opponent could avoid it, which was comparatively easy given that most early torpedoes left behind a tell-tale trail of bubbles in their wake. Torpedo boats were small and could easily be sunk by gunfire. By night the risk from gunfire was less, but the invention of the searchlight made it possible to keep the waters round a ship under observation all night. From the torpedo sprang too the submarine, which aimed at striking below the surface, where it itself was, like its weapon, invisible, or nearly so. The Russo-Japanese War The Russo-Japanese War was the first test of the new concepts. The war was a stunning victory for Japan, opening with the blockade and gradual immobilization of the Russian Pacific Fleet at Port Arthur and culminating in the destruction of the Russian Baltic Fleet at the Battle of Tsushima in 1905. First use of torpedoes in battle In the war between Russia and Japan the torpedo was at first used with success, but the injury it produced fell below expectations, even when allowance is made for the fact that the Russian squadron at Port Arthur had the means of repair close at hand. In the sea fights of the war it was of subordinate use, and indeed was not employed except to give the final stroke to, or force the surrender of, an already crippled ship. Effectiveness of mines The war also saw the first use of mines as an offensive, rather than purely defensive, weapon when the Japanese laid a minefield outside Port Arthur. On April 12, 1904, the Russian flagship Petropavlovsk ran into the minefield off Port Arthur and was sunk, while the battleship Pobieda was badly damaged. The Russians turned the same tactic on the Japanese who lost two of their six battleships, the Yashima and the Hatsuse, in a newly laid Russian minefield off Port Arthur a month later. Sinking ships to block harbours The Russo-Japanese War (and as much may be said for the war between the United States and Spain) confirmed an old experience. A resolute attempt was made by the Americans to block the entrance to Santiago de Cuba with a blockship.