Containment shield

The containment shield was a massive energy barrier projected from the Sentinel Wall around Installation 05's Library. One of the many containment measures built by the Forerunners, it helped contain and enclose the Flood inside the Quarantine Zone, and keep out anything that could sustain the Flood. It had to be lowered and deactivated in order to enter the Library and recover the Activation Index.

History
During the Battle of Installation 05, the containment shield kept UNSC and Covenant forces stationed on Delta Halo from reaching the Index. In order to gain access to the Library and retrieve the Index, the Hierarchs of the Covenant dispatched Arbiter Thel 'Vadamee to lower the shield. The Arbiter fought his way through the Sentinel defenders to the enormous chamber containing the controls for the barrier. After destroying the Sentinel Enforcer guarding the chamber, the Arbiter retracted four piston-like plug locks which unlocked the main control panel, allowing him to lower the shield. This caused the entire two-tiered control platform to move to the other side of a large chasm in the middle of the Sentinel Wall in a manner similar to an anti-gravity gondola.

The deactivation of the shield allowed access to the Quarantine Zone by the Covenant and the UNSC, giving the Flood hundreds of new hosts. The Flood was released onto the rest of Installation 05. As a result of this, the was taken over by the Flood and flown into the Covenant city of High Charity.

Trivia

 * In Halo 2, the containment shield was observed during the level Sacred Icon.
 * The holographic control panel for the shield displays what appears to be a perfectly symmetrical hand with six fingers. Whether by coincidence or not, this matches the later depictions of Forerunner hands in Halo 4 and The Forerunner Saga, which establish most Forerunners as having six-fingered hands with two thumbs.

List of appearances

 * Halo 2