In 2491, Doctor Elias Carver published a series of findings regarding the possibility of insurrection in the outer colonies.

In 2491, the Office of Naval Intelligence re-instituted the Orion Project, an attempt to create engineered super-soldiers to boost combat effectiveness.

The Far Isle Rebellion was a major uprising on the outer colony world of Far Isle in 2492 that is largely cited in spurring the Insurrection.

The Callisto Incident was a series of events involving the UNSC Callisto that is considered the first true insurrectionist attack from January to March 2494. 

Operation: TREBUCHET was a twelve-year UNSC operation to quell growing unrest and insurrectionist activities in the outer colonies from 2513 until the start of the Human-Covenant War in 2525.

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. 

Operation: JOVIAN WHISTLE was an operation executed by the UNSC 717th Xeno-Materials Exploitation Battalion to recover a Forerunner ancilla on the human colony world of Gao in the Cordoba system in the early summer 2553.