The Life Day massacre occurred during an improvised celebration of Life Day by the young Wookiee slaves on the Imperial Correctional Facility on Kessel.
The Wookiees planned the secret celebration during their mid-day meal break with help from Gyylghrard, who liaised with the Jawa overseeing the food storage. Gyylghrard managed to obtain rehydrated Corellian ryshcates with candles and sparksticks for the event.
After the meal, a female Wookiee began growling the melody of the Tree of Life, and the rest soon joined in. The candles were supposed to be lit for a single minute after the song, however the Wookiees simultaneously lit their sparksticks and overloaded their electronic shackles.
A fight ensued where the stormtroopers found their blasters drained of power. The adult slaves joined the fray and they found themselves overpowering the guards. The insurgents managed to take the fight to the launch bays before the stormtroopers, with recharged blasters, cut them all down with blaster fire. Gyylghrard later learned from Moruth Doole that it was ordered by the warden, Dewt Kluskine himself.
A few years later, Gyylghrard avenged their deaths when he was appointed as an honor guard of the warden. During a visit from Jabba Desilijic Tiure's accountant, Fossco, Gyylghrard took the opportunity to behead Kluskine with his Ceremonial poleaxe before being killed by the stormtroopers.