Operation: TREBUCHET

Operation: TREBUCHET was the UNSC's military response to the numerous civilian uprisings in the Outer Colonies known as the Insurrection. Spanning over ten years and encompassing at least two star systems, Operation: TREBUCHET involved numerous Marine units and many vessels from the UNSC Navy. It is one of the largest and farthest reaching operations known to have been conducted by the UNSC in its long history.

Overview
Beginning in 2513 with a large uprising in the Eridanus Star System, Operation: TREBUCHET was intended to be a heavy handed fight to bring all dissenting outer colonies in line, effectively crushing all resistance to the UNSC's authority in the outer colonies.

At first the aggressive response was widely accepted, however, as the fight dragged on and the theater of operations expanded, the continuing operation became extremely unpopular with the UNSC civilian population. Operation: TREBUCHET eventually became the central conflict for the UNSC armed forces, only being ended with the massive genocide that followed with the Human-Covenant War.

2511
Around 2511, the rebels had overthrown the colonial government of Eridanus II, and largely controlled all activities within the system. The UNSC responded harshly, seeking to put down the rebellion forcibly.

2513
Fighting broke out in the Eridanus Star System first, particularly at Eridanus II and the space around it, as rebels supporting the system's breakaway from the UNSC (labeled Insurrectionists by the UNSC) built a small navy of civilian craft and attempted to take over the system. The disorganized Eridanus Rebels were eventually brought together by Colonel Robert Watts. The UNSC responded harshly, sending a Fleet of Destroyers and Carriers to the system to combat the rebel fleet. The resulting battle pitted UNSC destroyers and carriers, against at least one hundred smaller rebel vessels. The UNSC forces defeated their rebel counterparts with little difficulty, however four of the UNSC destroyers were lost in the engagement. During the battle, the rebels were routed and the remnants of their fleet fled into an asteroid belt in Eridanus Secundus. They would eventually establish a fully functional asteroid base and began conducting raids again by 2525.

A ground campaign was begun on Eridanus II as well, as units from the 9th Marine Expeditionary Force were sent to the planet in force, hoping to capture leaders of the movement and pacify the population. One of these units, 1st Battalion of the 21st Marine Division commanded by Lieutenant Colonel Ponder, was involved in a disastrous mission to try and capture a leader of the rebels in Elysium City, which ended in the leader's family being killed and Ponder wounded and demoted.

2524
Fighting continued in Epsilon Eridanus up to and including 2524, by this point it had taken over a million lives, mostly civilian. A different Marine Battalion was posted at colony world Tribute, commanded by Lieutenant Colonel Aboim and supported by the corvette UNSC Bum Rush and air support from Hornets. The battalion attempted to put down rebel bomb makers. Two special warfare squads, led by Staff Sergeant Avery Johnson and Staff Sergeant Nolan Byrne, were involved in yet another disastrous operation in June of 2524, in which Byrne's team was killed during a hostage situation at a Jim Dandy restaurant near Casbah city. Thirty-Eight civilians, three Marines, and two rebels were killed in the bombing. Byrne and Johnson were pulled from the system, and later sent to Harvest.

In the meantime, the Insurrectionists resorted to bolder, more deadly tactics, such as the bombing of a civilian liner in orbit over Reach.

2525
This is the last known operation involved the SPARTAN-II soldiers in 2525. A team of five SPARTAN-IIs was dispatched and sent to infiltrate the rebel base at Eridanus Secundus and capture Watts, the rebel leader. They succeeded in doing so, crippling but not destroying the rebel infrastructure in the Eridanus system. The operation was abruptly concluded with the start of the Human-Covenant War after the Battle of Harvest. Though the Insurrection continued for a long time, the rebel threat in the system was rapidly decreased when the genocidal Covenant destroyed the systems, glassing planets and killing every human they encountered. In the meantime, many of the rebels, seeing that the UNSC offered the only real protection against the overwhelming Covenant force, ceased to resist, and either submitted to the UNSC's control or hid themselves away from both UNSC and Covenant attack. Some groups of rebels survived free of UNSC control for as long as 2552. The majority simply continued their daily lives without interfering with the UNSC.