From Halopedia, the Halo wiki
The UNSC All Under Heaven was a carrier of the United Nations Space Command. In 2545, it was assigned to the 51 Pegasi system as the staging ground for Operation: TORPEDO. It launched the 300 Spartan-IIIs of Beta Company in Long Range Stealth Orbital Insertion Pods while still in slipspace.
Its name is a reference to an ancient Chinese cultural and political concept known as tianxia (Chinese: 天下) which translates to "all under heaven."
List of appearances