This section concerns content exclusive to Warcraft III.
Snarlmane was the leader of a gnoll group in Tirisfal Glades and was caught in between a conflict involving Varimathras and Sylvanas during the third war. Sylvanas used one of her banshees to possess Snarlmane and use his Gnolls in suicide assaults against Varimathras' forces.[1]
As he is now undead and found among the other Rot Hide gnolls in habiting Fenris Keep, it seems safe to say he was killed during the conflict and later raised by the Scourge.