The Spartan II program, led by Dr. Catherine Halsey, was a plan by the Office of Naval Intelligence to use children with superior genetic traits to create a group of super-soldiers in order to put an end to the ongoing Insurrection in the outer colonies. 

Spartan-III Alpha company was the first of three Spartan-III companies to be recruited, trained, and put into service.

Spartan-III Beta company was the second of three Spartan-III companies to be recruited, trained, and put into service.

Spartan-III Gamma Company was the last of three Spartan-III companies to be recruited, trained, and put into service.

The Onyx Conflict was a major engagement between UNSC, Covenant, and Forerunner forces on and around the planet of Onyx in the Zeta Doradus system in October and November 2552.