As for the assailants, as soon as they saw conclusive proof that the blockade had been broken and the city victualled, they found themselves deserted by the ally on whose aid they had most counted. While the grip of famine remained on London they knew that its fall was only a matter of time; but now--if food could get in so could reinforcements, and they had not the remotest idea as to the number of the mysterious forces which had so suddenly sprung into existence outside their own lines. Added to this their losses during the night had been something appalling. The streets were choked with their dead, and the houses into which they had retired were filled with their wounded. So they, too, were glad of a rest, and many spoke openly of returning to their lines and abandoning the assault. If they did so it might be possible to fight their way to the coast, and escape out of this huge death-trap into which they had fallen on the very eve of their confidently-anticipated victory. So, during the whole of the 7th there was little or no hard fighting in London, but to the north and south the grey legions of the Federation fought their way mile by mile over the field of Armageddon, gradually driving in the two halves of the Russian and the Franco-Italian armies which had been faced about to oppose their progress while the other halves were making their assault on London. As soon as news reached the Tsar that the blockade of the river had been broken, he had ordered twelve of his remaining war-balloons to destroy the ships that were swarming below London Bridge. Their fuel and cargoes of explosives had been renewed, and they rose into the air to execute the Autocrat's command just as Natasha had taken leave of Arnold on her errand of mercy. He fathomed their design at once, swung the _Ithuriel_ rapidly round to the northward, and said to his lieutenant, who had just come on deck-- "Mr. Marston, those fellows mean mischief. Put a three-minute time fuze on a couple of No. 3 fire-shell, and load the bow guns." The order was at once executed. He trained one of the guns himself, giving it an elevation sufficient to throw the shell over the rising balloons. As the sixtieth second of the first minute passed, he released the projectile. It soared away through the air, and burst with a terrific explosion about fifty feet over the ascending aerostats. The rain of fire spread out far and wide, and showered down upon the gas-holders. Then came a concussion that shook the air like a thunder-clap as the escaping gas mixed with the air, took fire, and exploded. Seven of the twelve aerostats instantly collapsed and plunged back again to the earth, spending the collective force of their explosives on the slopes of Muswell Hill. Meanwhile the second gun had been loaded and fired with the same effect on the remaining five.