Sheildum

Sheildum was a planet in the Outer Colonies that was glassed by the Covenant in 2540. Soon after it's Glassing, the 128 Spartans of Incognito Company were sent to the world to eliminate these Covenant.
The world was retaken days later by UNSC forces. It was also the homeworld of Abbad Reiken. 
Soon after the Human-Covenant War ended, the planet was terraformed and soon was recolonized by many refugees who had been displaced due to the war. Many war veterans also were sent to the world due to its peaceful nature, allowing them to deal with their past uninterrupted. It was mostly considered unimportant during the Human-Created Conflict, and thus was mostly left alone.
During the UNSC-HOS War, a small group of Hand sympathizers grew and began wreaking havoc on the world, bombing the cities that many had worked hard to build. However, this presence was quickly dealt with soon afterwards.