In 2256 the USS Discovery used its experimental spore drive to jump to the besieged dilithium colony on Corvan II and destroy the Klingon ships attacking it.
Corvan II was a mining colony that supplied a large share of the Federation's dilithium, and Klingon forces were bombarding it. Starfleet had no ship close enough to save it, but Discovery's spore drive could in theory carry the ship there instantly.
Michael Burnham found that the creature Ripper could interface with the mycelial network, and with its help Discovery jumped to Corvan II, destroyed the attackers and saved the colonists. The victory made Discovery a vital weapon, but it came at a heavy cost to the tardigrade.