Battle of the Silent Cartographer

The Battle of the Silent Cartographer was a brief conflict on Installation 04, during the Human-Covenant War. A part of a much wider conflict in 2552, the battle produced numerous casualties on both sides and resulted in the UNSC's discovery of the Control Room's location.

The battle
SPARTAN-II John-117 and two squads of marines were ordered by Captain Keyes to insert into the Covenant-held island and reach the Cartographer in order to locate Halo's control room.

The soldiers landed via Pelican dropship on a heavily defended beach, but quickly took out all enemies in sight. The Master Chief and two Marines in his Warthog continued along the beach in search of entrances to the island, while the Marine squads held position under an enormous Forerunner structure.

The Chief and squadmates managed to fight their way into the facility's main entrance despite significant resistance, but the last Covenant squad guarding the entrance managed to lock a key door and impede UNSC progress before being wiped out. Ultimately, the effort was futile, because (thanks to poor Covenant inter-squad coördination) the Chief was able to singlehandedly eliminate all personnel guarding the island's security controls and disable all locks in the facility.

The Chief, again demonstrating superb infiltration and special operations skills, then resumed his mission into the depths of the facility, bypassing all Covenant resistance on the way, and successfully allowed the AI Cortana to retrieve the relevant information on the Control Room and Halo's subsystems.

Repeated Covenant attempts to eliminate the Master Chief - including by Hunters and squads of Stealth Elites - were unsuccessful. The Chief and Cortana withdrew from the island intact; by virtue of Cortana's new knowledge of the ring, they and Echo 419 were able to descend the facility's main shaft and navigate the Installation's underground tunnels to the Control Room.

Other
It is not stated in Halo: The Flood how many marines participate, but in the game you are given a number of them varying on the difficulty you are on. Easy will give you nine, but heroic will give you seven. The book only mentions two Warthogs and not the wrecked one you find by the beach in the game.

The fate of the two squads that accompanied the Chief to the island is unknown, although they are believed to have suffered heavy casualties in both the initial beach assault and in assisting the Chief on his daredevil insertions underground.