Besides the _Vala_ and _Prince Charles_, three other Q-ships were fitted out in the north. These were the _Glen Isla_, of 786 tons; the _Duncombe_, 830 tons; and the _Penshurst_, 740 tons, and they all performed excellent work. But before we go any further we have to consider still another novelty in naval warfare, or rather a strange revival. Who would have thought that the sailing-ship would, in these days of steam, steel, and motor, come back in the service as a man-of-war? At first it seems almost ludicrous to send sail-driven craft to fight against steel, mechanically propelled vessels. But, as we have seen, this submarine warfare was not so much a matter of force as of cleverness. It was the enemy’s unimaginative policy which brought about this reintroduction of sail into our Navy, and this is how it all happened. During the summer of 1915 German submarines in the North Sea had either attacked or destroyed a number of neutral schooners which used to come across with cargoes of pit-props. One used to see these fine little ships by the dozen arriving in the Forth, for the neutral was getting an excellent return for his trading. It annoyed the enemy that this timber should be able to enter a British port, and so the submarines endeavoured to terrorize the neutral by burning or sinking the ships on voyage. It was therefore decided to take up the 179-ton schooner _Thirza_, which was lying in the Tyne. Her purchase had to be carried out with great secrecy, lest the enemy should be able to recognize her at sea. She was an old vessel, having been built as far back as 1865 at Prince Edward Island, but registered at Whitstable. She changed her name to _Ready_, and began her Q-ship service at the end of August, 1915, when soon after midnight she sailed down the Forth. Armed with a couple of 12-pounders, having also a motor, carrying a small deck cargo of pit-props, and suitably disguised to resemble a neutral, this schooner, manned by a hardy volunteer crew, used to pretend she was coming across the North Sea, though at first she never went many miles away from the land. Under the various aliases of _Thirza_, _Ready_, _Probus_, _Elixir_, and Q 30, this old ship did splendid work, which did not end until Armistice. We shall have occasion to refer to her again.