As soon as these orders had been despatched the _Avenger_ left Moscow, and started at full speed for Gibraltar, where she arrived about four o’clock in the afternoon. Here Alan, after once more inspecting the land batteries and the aerial defences of this important outpost of the Federation, received news of the annihilation of the four Moslem expeditions, and heartily congratulated Admiral Ernstein on the complete success of his operations. It was at once apparent that the Sultan would not risk a second loss so enormous as this even if he had sufficient transports left and could persuade any more of his people to brave the terrors of such another sea-fight. This being so, only two alternatives would be open to him, either he must give up all idea of invading Europe by land or sea, or else he must attempt to force the bridges across the Dardanelles and the Straits of Gibraltar, and cross into Europe _viâ_ Turkey and Spain. Both these bridges, the main highways between Europe, Africa, and Asia Minor, were guarded on the European side by batteries of enormous strength, similar to those which guarded the Federation posts in the Mediterranean. They were magnificent structures, each four hundred feet broad, carrying twelve lines of railway as well as carriage drives and promenades, and, once in the hands of the enemy, troops could be poured across them in tens of thousands every hour. Alan, after a brief conference with Ernstein, decided to pursue the same tactics here as he was going to make use of on the Russian frontier. The bridges were to be left completely open, but their supporting pillars were to be mined with torpedoes, connected by electric wires with the batteries. If the Sultan attempted to force them, his men were to be allowed to concentrate on the African and Asiatic shores and to occupy the bridges, then the bridges were to be blown up and the forces on the opposite side to be dispersed by the batteries and the air-ships. The message to the Dardanelles bridge was despatched by telephone over the cables connecting Gibraltar with Candia and Gallipoli, and similar instructions were sent on from Gallipoli to Constantinople, in case any attempt should be made to force the bridge which spanned the Bosphorus. The Mediterranean patrol was to be maintained as before, and three air-ships were sent out to reconnoitre the African coast from Ceuta to Port Said during the night, and learn what they could of the Sultan’s intentions. The rest of the evening and the greater part of the night were spent by Alan receiving and answering reports from the northern coast of the Mediterranean, the Russian frontier, and the principal cities of Europe, and in assuring himself that everything was ready, so far as was possible, to meet the storm that must infallibly burst over the Continent within the next few days.