Federation–Klingon War (2256–2257)

The Battle at the Binary Stars in 2256 opened the first full-scale war between the Federation and the Klingon Empire. Inspired by the martyred T'Kuvma, many Great Houses rallied behind his idea of resisting the Federation's influence, and Klingon cloaking technology gave them a dangerous advantage.

The USS Discovery, under Captain Gabriel Lorca, became one of Starfleet's key assets thanks to its experimental spore drive, which allowed near-instant jumps across space. Michael Burnham, released from prison to serve aboard, helped crack the Klingon cloak at Pahvo. But when Discovery was stranded in the mirror universe for months, the Klingons pressed their advantage, overrunning Federation territory and approaching Earth.

Desperate, Starfleet approved a plan to destroy the Klingon homeworld Qo'noS and sent the mirror Philippa Georgiou to carry it out. Burnham refused to accept genocide and instead gave the device to the Klingon L'Rell, who used the threat it represented to unite the Great Houses under her leadership and end the war in 2257. The conflict cost many lives and left a deep mark on relations between the two powers, which remained tense for decades.