Halo Alpha
Halo Alpha

Operation: TREBUCHET was the Unified Earth Government'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.[3]


In 2494, Insurrectionist forces take control of Eridanus II, establishing their own secessionist government in the wake of the coup d'état.[4]

In 2496, UNSC forces began their campaign to retake the planet, deploying a battlegroup of unknown size to engage the makeshift Insurrectionist defense fleet. Despite the UNSC's best attempts at removing the entrenched rebellion, ONI failed to discover the location of their base. This hollowed-out asteroid would remain a safe haven for Insurrectionists for another three decades.[4]



Beginning in 2513 with a large uprising in the Eridanus system, Operation: TREBUCHET was intended to be a heavy handed fight to bring all dissenting Outer Colonies in line, effectively crushing all resistance to Earth's authority in the Outer Colonies.

Fighting broke out at Eridanus II and the space around it, as rebels supporting the system's breakaway from the UNSC build a small navy of civilian craft and attempt to take over the system. The disorganized Eridanus Rebels are eventually brought together by Colonel Robert Watts.

The UNSC responds harshly, sending a Fleet of Destroyers, Carriers, and Cruisers to the system to combat the rebel fleet. The resulting battle pitted the UNSC against at least one hundred smaller rebel craft.[2] The UNSC forces defeated their rebel counterparts with little difficulty. During the battle, the rebels were routed and the remnants of their fleet fled into the asteroid belt to Eridanus secundus. They would eventually establish a fully functional asteroid base and began conducting raids again by 2525.[2]

A ground campaign begins on Eridanus II, as units from the 9th Marine Expeditionary Force are sent to the planet in force, hoping to capture leaders of the movement and pacify the population. One of these units, the first Battalion of the 21st Marine Division commanded by Lieutenant Colonel Ponder, was involved in a disastrous mission to try and capture a rebel leader - the second in command - in Elysium city, which ended in the leader's family being killed and Ponder wounded and demoted.[5]

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 human civilian population. Operation: TREBUCHET eventually became the central conflict for Earth's premiere fighting force, the UNSC.

Epsilon Eridani[]

Fighting continued all the way to 2524, spreading to Epsilon Eridani. By this point, the war had taken over a million lives, the majority of which being civilians. A Marine Battalion was posted at the colony world of Tribute, commanded by Lieutenant Colonel Aboim and supported by the corvette UNSC Bum Rush and air support from Hornets. The battalion attempted to put a stop to rebel bomb makers. Two special warfare squads, led by Staff Sergeants Avery Johnson and Nolan Byrne, are involved in a disastrous operation in June. Byrne's team is killed during a hostage situation at a Jim Dandy restaurant near Casbah city. Thirty-Eight civilians, three Marines, and two rebels are killed in the bombing. Byrne and Johnson are pulled from the system, and later sent to Harvest.[6]

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


The operation was abruptly concluded with the start of the Human-Covenant war after the First 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.[7] 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. Others even decided to offer dealings with the UNSC. However, most of these dealings were traps.

Following TREBUCHET, a team of five SPARTAN-IIs were dispatched to infiltrate the rebel base at Eridanus secundus and capture Watts, the rebel leader in 2525. They succeeded in doing so, crippling but not destroying the rebel infrastructure in the Eridanus system.[8]

The rebel base in the Eridanus system was marked for further attack, but for some reason, likely due to the greater threat the Covenant posed, it was left alone and mostly forgotten until 2552 when Vice Admiral Danforth Whitcomb and a small crew including the AI Cortana and several Spartans (including all but one of the team that attacked the base) returned looking for repairs. After being convinced to help by a Covenant attack, the rebels repaired the Ascendant Justice-Gettysburg to operational status, but the two ships were too badly damaged to be fully repaired before the Covenant returned. The UNSC forces were forced to abandon the rebels. The base and the rebels have been presumably destroyed.



  • The URF attempt to take over Eridanus II. A UNSC counter attack takes place.





Naval Assets[]

Class Name Status
UNSC corvette UNSC Bum Rush Unknown

Military Personnel[]

Branch Rank Name Status
UNSC Navy Unknown James Cutter Survived
UNSC Marine Corps Lieutenant Colonel Aboim Unknown
Ponder Survived
Staff Sergeant Avery Johnson Survived
Nolan Byrne Survived
Unknown Daniel Black Survived
Colonial Military Administration Unknown Felicia Sanderson Survived
Gage Yevgenny Survived
Eric Santiago Survived
Allison Stark KIA


Naval Assets[]

Class Name Status
Unknown Iliad Survived


  1. Halo Waypoint: Canon Fodder - Bulkhead Banter
  2. 2.0 2.1 2.2 Halo: The Fall of Reach - pages 75-77
  3. Halo: Contact Harvest - page 11
  4. 4.0 4.1 Halo: The Fall of Reach - pages 17-18
  5. Halo: Contact Harvest - page 112
  6. 6.0 6.1 Halo: Contact Harvest - pages 9-20
  7. Halo: First Strike - page ??
  8. Halo: The Fall of Reach - page 83
  9. Halo Wars - Collectible: Halo Timeline