Nuclear weapon
From Gineipaedia, the Legend of Galactic Heroes wiki
Use of nuclear weapons on inhabited planets has been taboo ever since the Thirteen Day War resulted in a nuclear apocalypse that almost wiped out human life on Earth.
Laser Fusion Missiles
These missiles were the standard form of anti-ship missiles and used inertial confinement fusion. A strong gravitational field generator kept a sphere of hydrogen compressed into metallic form. High energy lasers heated this to over 300,000,000 degrees Celsius, compressing and heating the sphere sufficiently for a nuclear fusion reaction.
Warhead yields varied, ranging from kiloton scale tactical warheads to gigaton scale strategic planetary warheads.
It is estimated that as of 798 UC (489 IC / 3598 CE), over 100 different types of missile were used by the fleets of the Free Planets Alliance. The standard Free Planets Alliance anti-ship laser fusion missile of that time had a diameter of 2 metres, a length of 10 metres, and used a deuterium fusion reaction for propulsion. It was capable of a maximum acceleration of 10G. (Fleet File Collection Vol.4, Data Book: Mechanic & Seiyū Encyclopaedia, p. 183, 184)
Missile launcher systems further accelerated missiles upon launch using electromagnetic fields. The launchers on board the Patoroklos were capable of accelerating missiles at 6G. (Fleet File Collection Vol.2)
