Fourth Siege of the Black Gate

The Fourth Siege of the Black Gate saw the end of the Dragon Event, as after the battle of Helm's Deep Legolas had been captured by a second dragon whom bore him to the pits of Udûn. This was partly the reason why the Mallorn Council and Rohan were quick to countersiege the Black Gate, hoping to break their string of losses on the Southern Front.

Prelude
Having just won the Battle of Helm's Deep, the Mallorn Council sans Legolas and Edrahil marched south. Reaching the Black Gate in record time, they sought to siege Sauron's tired garrison and finally win a siege of the Black Gate once more. Yet arriving, they saw Sauron's forces had been bolstered, and he met them in battle eagerly.

Battle
A rohirric cavalry charge was quickly repelled, with Reinwald retreating early on to avoid death. This left the elven forces without proper auxiliary support, and they were quickly overwhelmed by Sauron's mace. Yet 12 kilometers into Mordor, Legolas was still struggling with the dragon. The dragon had flown into a ravine, and after trying to eat Legolas for several minutes, fallen asleep. Legolas then killed the dragon, aiming his best arrow through the slit of the dragon's closed eye.

Aftermath
Though Sauron won the battle, Legolas managed to slay a dragon which Sauron could have corrupted into his service. Moreover, Legolas' dragon slaying sparked a Dragon Egg event, where heroes and villains alike searched the world for dragon eggs.