493 PT
Non-competing
Over time the several nations of Cythera (terraformed Venus) and the colonies on Mercury all joined the Republic of Splodesisa. Mars is still called Mars. In a similar way Muskovia became the only nation on Mars. Earth advanced science and technology.
Sometimes they were friends, sometimes not, but they settled their differences with words. No longer. The previously peaceful Muskovites have a shield and leaders desiring an empire. The shield is a bit of science fiction made real but it only works on a very large scale so they have enclosed the whole of Mars in one while they build up forces for conquest. If the Earth-Splodesia alliance can act while Muskovia is still militarily weak then this can end with a minimum of harm. But the shield …
On 493 PT (post terraforming) 68% day cycle several vessels carrying Splododyne Explodiatory Explodolators began the journey to Mars. The yields have been set to just enough to take down the shield.