At approximately 2:34 PM, the approximately 5 kiloton nuclear explosion happened without any warning, the pressure wave hitting the city scant seconds later. The fireball was fortunately well out of range, preventing massive devastation. However, the blast shattered windows, knocked down fragile walls, and capsized several ships, as well as scattering small amounts of radioactive fallout over the southern edge of the island. No casualties were caused as a direct result of the blast, but the fallout claimed approximately five lives and poisoned others, killing crops and livestock.
In either case, the blast provided the perfect causus belli for the Houses, and the perfect reason to begin the Second Infinitas War.
The blast is remembered vividly in the memory of the town for the shock, terror and panic that it caused, and knowledge of it is commonplace. The fallout remains in Marsilion's area, but has quickly decayed to the point at which only low-level radiation remains, scarcely above background levels, leaving this explosion an exclamation mark upon the book of history.
The origins of the explosion are unknown, with each of the Great Houses initially blaming the explosion each other, and then later the Marsilion Government when it later arose. Propaganda leaflets later dropped by Saber claimed that the blast was intended to scare citizenry in order to blind them to the war. The nuclear explosion did not seem to be the result of a missile or bomb, but rather a ground explosion of some sort.
The true origins of the explosion may forever remain a mystery, but so far, no evidence of other nuclear devices seems to exist upon Infinitas, and the capacity to manufacture a nuclear bomb remains (supposedly) out of reach of all current governments on the isle.