From Halopedia, the Halo wiki
Pervading Stone was the leader of the Keepers of the Dawn, the first San'Shyuum to be called Prophets. Having lost his father during the ground siege at Ulgethon in the first major battle of the War of Beginnings, he spent years laying waste to Sangheili colonies and outposts despite the events at Codisfold. Silencing dissenters and elminating them when necessary, he continued his baleful campaign which he saw as the complete annihilation of all the Sangheili. After discovering the location of their homeworld, he ordered the Dreadnought to Sanghelios for one final attempt to sever the head of their foe. This led to an unexpected and decisive response from the Sangheili, who were eventually able to down the Dreadnought and storm the ship. Despite pleas from San'Shyuum advisers to consider striking a truce with the Sangheili, Stone refused to back down, leading to his death at the hands of his enemies.