The Elven Defenders was a high elven organization tasked with defending Quel'Thalas and by the time of the Third War they answered to the ranger-general of Silvermoon, Sylvanas Windrunner. When the Undead Scourge led by Prince Arthas attacked the kingdom, the Scourge was forced to fight the Elven Defenders regardless of which forest area they decided to move through. During the battle that followed the Elven Defenders were beaten back and the Scourge was able to move past the Outer Gate and move further into Quel'Thalas.
Forced to retreat the Elven Defenders joined the Elven Ranger Corps, defending the Inner Gate and guarding the only way to open it. The Elven Defenders were ultimately annihilated by the Undead Scourge as they claimed the Key of the Three Moons and advanced further into Quel'Thalas.