And so did Aragorn son of Arathorn gather as many soldiers as possible to come with him to the Black Gate of Mordor and fight one last time against the Host of Mordor. The two friends, Ornessar and Katrandil, joined him too.

There, they met a defiled Númenórean, called "The Mouth of Sauron", who conversed with Aragorn. This event started the battle. The Black Gate opened, and Aragorn turned towards his allies.
