Of course these conditions played havoc with salvage concerns. The fortunes that might have been locked up in war wrecks quietly vanished. It must be borne in mind that enemy torpedoes in the first place had done enormous damage to the sunken ships, and what the torpedoes had left undone the storms of the Armistice years had finished. The immersion of a ship for a year or two in the sea, with the consequent rust set up in the metal, works sorry havoc, while sand and mud swirling about in the engine-rooms tend not to improve the engines. Every hour that a ship spends on the ocean bed she deteriorates in value. Mud is silting into her, sand and rust are gnawing away at her, the swell is shaking her continuously. The sea soon finds out the weak spots and hammers at them until the whole structure collapses into a fantastic mass. It can be imagined what some of the war wrecks were like after a thousand days of such treatment. They were not worth salving, for no salvage concern would risk thousands of pounds just to recover a little scrap metal. These factors eventually led to a cessation of salvage activity around our shores. For long after the Admiralty Salvage Section had ceased to operate in home waters, one or two units were working on the Belgian coast, struggling to clear the harbours of Ostend and Zeebrugge from the ships that British sailors had so gallantly sunk in order to prevent the Germans from using them as submarine bases. When the _Vindictive_ went down in her allotted place, she covered the British Navy with glory. All the might of Germany, all the skill of which she boasted, failed to move the sunken ship from the spot where the British had placed her. The Germans did their uttermost--for they were anxious to use the harbour--but they were beaten. The genius of the Admiralty Salvage Section, Commodore Sir Frederick Young, studied the problem. The _Vindictive_ was not only full of cement, which had set hard directly the water ran into it, but there were also many mines aboard, and no one knew whether all these mines had gone off or whether some of them were still alive. Added to the problem of the _Vindictive_ was the fact that the Germans, in their retreat, had sunk all sorts of craft in the harbour to bottle it up completely, and ensure that the Belgians would never use Ostend again without going to an awful amount of trouble.