The main fleet of the Solar System was already on its way, and every moment drew closer to this running battle, for the great ships of the Nigrans had, although they were entering the system cautiously, been going at a very high speed, as interplanetary speeds are measured. The entire battle had been a running encounter between the two forces. The Solarian force, invisible because of its small size, was certainly getting the better of the encounter thus far, but now that the odds were changing, now that the small ships had come into the fray, engaging them at close range, they were not having so easy time of it. It would be many hours before the full strength of the Solarian fleet could be brought to bear on the enemy. They were not able to retire and await their arrival, for they _must_ delay the Nigran fleet. If even one of those great ships should safely reach the two planets behind them--! But within a half hour of the original signal, the Rocket Squad had thrown itself into the battle with a fervor and abandon that has given that famous division a name that will last forever. The small fliers of the Nigrans were beginning to take an appalling toll in the thinning ranks of the Solarians. The coming of the Rocket Squad was welcome indeed! They were able to maneuver as swiftly as the enemy; the speedsters were harder to spot than the Solarian ten-man and thirty-man boats. The Solarian speedsters were even smaller than the comparable Nigran craft, and some of these did a tremendous amount of damage. The heat ray was quite ineffective against the ten-man ships, even when working at full capacity, when produced by the small generators of the Nigran one-man boats. The cruisers could absorb the heat and turn it into power faster than the enemy could supply it. Beams from the monster interstellar liners were another matter, of course. But the one-man speedsters had a truly deadly plan of attack against the liners. The plan was officially frowned upon because of the great risks the pilots must take. They directed their boats at one of the monster ships, all the power units on at full drive. As close to target as possible the man jumped from his ship, clothed, of course, in an altitude suit equipped with a radio transmitter and receiver. Death rays could not stop the speedsters, and with their momentum, the invaders could not make it less deadly with their heat beam, for, molten, it was still effective. A projectile weighing twenty-two tons, moving a hundred miles a second, can destroy anything man can lift off a planet! Their very speed made it impossible to dodge them, and usually they found their mark. As for the risk, if the Solarian forces were victorious, the pilots could be picked up later, provided too long a time had not elapsed!