The colony and system of Sheshisimal were settled in 1801 CE, at the early phases of cluster's second immigration wave. The garden world had vast untapped potential in means of raw resources to exploit. Decade later in 1811, when prospectors publicized their findings of great gold and palladium deposits to attract workforce and investments, neighbouring great powers Joseo and Velka reasoned the rich world would better serve each state better under their direct control.
Both nations sent major task forces to take control of Sheshisimal, which also possessed defending forces of its own. The Sheshisimal Defence Force, however, was mainly an anti-pirate force and thus woefully inadequate to respond against the Velkan and Joseoan militaries. They were caught in the crossfire and vanquished in the first months of the war. Joseoan and Velkan ground forces pressed on, indifferent to the plight of the settlers whose homes were being demolished as the two powers sought to gain decisive control of key locations. As both combatants had troops on Sheshisimal’s surface and intended to capture the planet without razing all its development to the ground, orbital bombardment was ruled out. However, this left the two opposed armies equal, with no clear path to victory beyond a war of attrition.
The situation changed for the worse when Joseoan military commander Paruin Krecs, desperate to gain the upper hand over the Velkans, finally authorized the use of tactical nuclear weapons. The first few detonations routed several Velkan divisions and finally tipped the scales in favour of Joseo, but this victory was short-lived. A Mutually Assured Destruction scenario was triggered, with Velka authorizing a response in kind. All pretenses of preserving the garden world were finally discarded, permitting total warfare. As a result, Sheshisimal’s delicate biosphere was obliberated and the world was cast into a nuclear winter. The war ended in a draw, with both Joseo and Velka abandoning the now-worthless battleground.