The Battle of Borgia 009 was fought on and above the planet Borgia 009, in the Borg Regions, amongst the Diadochi on July 7, 2399. The battle took place between the forces of Antigonus I the Old and his son Demetrius, and those of the Coalition of the Four (comprised of Alexandra I Nicator, Hycranus I the Fat, Devraldus I the Mutilated, and Athanasius I the Energetic). The battle had arisen out Antigonus's campaigns against and aggravation of his fellow Diadochi, which had prompted them to ally in a military coalition in 2397 and launch an invasion of Antigonia. The Allies captured much of his dominions and struck deep into his territory. Antigonus assembled his armies and fleets for a blow against them which he believed would drive them out. However, he was hopelessly outnumbered by the Coalition Diadochi, despite his Borg army which was renowned for its power and organization. Antigonus was nevertheless crushed in the battle. Borgia 009 fell to the Coalition, his fleets were destroyed, and the old Emperor himself was killed. The decisive battle lead to the division of Antigonus's Empire amongst the Coalition Diadochi.
Of the Coalition of the Diadochi, Alexandra and Hycranus provided the greatest percentage of the naval forces used against Antigonus (about 64% of the total, 52% of that provided by Alexandra and 48% by Hycranus), while Devraldus provided the most Imperial infantry (69% of the total) and Athanasius a significant percentage of the other Star Trekian infantry (55%).