Dreadnoughts are kilometre-long capital ships mounting heavy, long-range firepower. They are only deployed for the most vital missions. A dreadnought's power lies in the length of its main gun. Dreadnoughts range from 800 metres to one kilometre long, with a main gun of commensurate length. An 800-metre class accelerator is capable of accelerating one two-kilogramme slug to a velocity of 283 km/s every two seconds. Each slug has the kinetic energy of 38 kilotons of TNT, three times the energy released by the fission weapon that destroyed Hiroshima.