The Federation-Mantis War lasted from 2664 to 2673. It began when the Mantis besieged the pro-Federation planet of Borch in June 2664. 4 attempts were made to relieve the siege, and while the first 3 failed, the fourth succeeded at forcing the Mantis to retreat. The Federation attempted to follow up this victory with an invasion of Mantis territory in 2665, which proved largely unsuccesful. A bitter stalemate continued until 18 July 2673, when the warring parties signed the Alsace Accords, ending hostilities. The Federation-Mantis War was marked by a large increase in anti-Mantis sentiment in the Federation, as well as a surge of Human supremacy. As such, it is believed to be a large factor in the causes of the Federation Civil War.

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