The fleet flew on, hills and rivers a silver-lit panorama unreeling beneath them. Earth's crescent sank behind them, and by the time they flashed out over the great fresh-water sea, the sun was rising like a flaming eye from behind it. Land sank from sight behind and the green men were silent, tense, as they saw stretching beneath only the gray waters that for ages had been the base of the dread frog-men. But still the fleet's column raced on. * * * * * At last the column slowed. Far ahead the merest bulge broke the level line where sky and waters met. The amphibian city of the Ralas! At Fellows' order-the flying-boats sank downward until they moved just above the waters. Another order made the green hosts don the grotesque helmets. Norman found that while cumbersome their oxygen supply was unfailing. They shot on again at highest speed, but as the gigantic black dome of the frog-city grew in their vision there darted up from around it suddenly a far-flung swarm of black spots. "Rala boats!" The muffled exclamation was Fellows'. There needed now no order on his part, though. Like hawks, leaping for prey, the fleet of the green men sprang through the air. Norman, clutching the force-gun between his knees, had time only to see that the Rala craft were a few hundred in number and that, contemptuous of the greater odds that favored these humans they had so long oppressed, they were flying straight to meet them. Then the two fleets met--and were spinning side by side above the waters. Norman saw the thing only as a wild whirl of Rala boats toward and beside them, great green frog-men crowding the craft, their force-guns hailing shells. Automatically, with the old air-fighting instinct, his fingers had pressed the catch of the gun between his knees and as its shells flicked toward the rushing boats he saw areas of nothingness opening suddenly in their mass, shells striking and exploding in annihilating invisibility there and in their own fleet. The two fleets mingled and merged momentarily, the battle becoming a thing of madness, a huge whirl of black and glittering flying-boats together, striking shells exploding nothingness about them. The Ralas were fighting like demons. The merged, terrific combat lasted but moments; could last but moments. Norman, his gun's magazine empty, seemed to see the mass of struggling ships splittering, diverging; then saw that the black craft were dropping, plummeting downward toward the waves! The Ralas, stunned by that minute of terrific combat, were fleeing. Muffled cries and cheers came from about him as the glittering flying-boats of the green men shot after them. They crashed down into the waters and curved deeply into their green-depths, toward the gigantic dome. * * * * *