21st Space Assault Battalion

The 21st Space Assault Battalion (21st SAB/ODST), also known as the Black Daggers, is a veteran battalion of the Orbital Drop Shock Troopers, a special operations capable reconnaissance force of the UNSC Marine Corps. Unlike most ODSTs, the Black Daggers receive special training and equipment for zero-gravity operations.

Known personnel

 * Colonel Marmon Crowther - Battalion CO (Dagger Actual) - KIA 04/15/2526
 * Captain Zelos Cuvier - Alpha Company CO - KIA 03/18/2526
 * Lieutenant Nelly Hamm - Alpha Company, First Platoon CO (Later Captain, Cuvier's replacement)
 * Lieutenant Nolan Connor - Alpha Company, First Platoon CO (Hamm's replacement)

Insurrection
The Black Daggers have a long history of combating Insurrectionists. In 2525 alone, they stormed and captured eighteen insurrectionist facilities, in locations ranging from low planetary orbit to deep transitional space. At some point prior to March 2526, they led a raid on a United Rebel Front-controlled supply depot at Bomogin, capturing it before the rebels even knew they were there.

Operation: SILENT STORM
By March 8, 2526 they were assigned to Captain Halima Ascot's Task Force Yama for the duration of Operation: SILENT STORM, a mission with the goal of stealthily boarding and destroying as many Covenant vessels as possible and buy time for humanity. At this time, the battalion was led by Colonel Marmon Crowther. Although Captain Ascot had full authority over the task force, once the ODSTs and the complement of twelve Spartans were deployed, command would transfer to Colonel Crowther. During the slipspace journey to Biko, Staff Sergeant Avery Johnson began working with the Black Daggers as they trained against the Spartans. At first, the marines proved to be no match for the Spartans, but that all changed when Johnson introduced some new, unorthodox strategies. He began spending the "lives" of his men like coins, buying opportunities to deal hard blows to the Spartans. This was a tactic that no sane UNSC commander would utilize except in the most dire circumstances, but it was one that the Covenant was known to use often. While the Spartans continued to outclass the individual ODSTs, victory was no longer certain when facing large numbers who now knew how to coordinate an effective assault. Four days into the training, Colonel Crowther had the entire battalion of Black Daggers gather to be briefed on his plan to board and destroy Covenant vessels. The Spartans would be split up, with each of the twelve being assigned to a single platoon. They would be the ones carrying the nukes. However, John-117 disagreed with this plan and Johnson backed him up. Ultimately the plan would change to one more suited to the Spartans' skills.

Seoba and Biko
Upon arriving in the Kolaqoa system on March 18, Task Force Yama set course for Seoba and the abandoned ice quarry that had been selected to house their prowlers until the Covenant arrived. Eager to not waste time that could be used for training, Colonel Crowther decided that the Black Daggers and John-117's Spartans would practice a full-scale landing into the quarry, dubbed Operation: ICE DANCE. With the drop bays of the task force's s packed full with forty-two ODSTs each, it would take time for them all to be deployed into the moon's low gravity, which would have each platoon strewn across a thirty-kilometer area unless they slowed down. Because of the Spartans' seeming lack of experience, Crowther also had each of them at the back of the drop bays, making them the last to deploy and in the absolute worst position to provide support, according to John's assessment.

While on approach, Task Force Yama intercepted communications from the Biko Independence Army, revealing that they were in the process of preparing a coup against Biko's chancellor and that these insurrectionists were presently occupying the very same quarry that they were approaching. With the Vanishing Point doing its best to block any transmissions from the moon, Crowther announced to his men that Operation: ICE DANCE was no longer a drill and that their insertion would likely be hot. He also ordered them to eliminate any communications equipment that they came across while on the ground, in the event that the insurgents had found a way around the jamming. For operational security, all Black Daggers would identify themselves as members of the Chancellor's Guards to any insurrectionist captives.

Once the prowlers reached their designated drop off zones and began deploying off their infantry complement, the entrenched insurrectionists tore into the ODSTs with M41 Vulcans. As Lieutenant Nelly Hamm of Alpha Company's First Platoon was busy tending to a wounded trooper he had handed her, John-117 disobeyed orders and leapt from the to face the insurgents head-on, with the rest of Blue Team following his lead. They softened up the insurrectionists enough for many of the Black Daggers to deploy safely. Ghost Flight managed to disable the enemy's communications center in their attack run, but the Spartans soon had to focus on preventing them from repairing it to call for reinforcements. As a form of payback for disobeying orders, Lieutenant Hamm tricked the Spartans into being a distraction so that her men could stop the insurgents from repairing the relay themselves. With the relay permanently disabled and enough ODSTs safely deployed, the ice quarry soon fell under UNSC control. During the battle, Captain Zelos Cuvier, the commanding officer of the Black Dagger's Alpha Company, was killed, resulting in Crowther promoting Lieutenant Hamm to the rank of captain and the new commanding officer of Alpha Company.

The very next day, Crowther's men had repurposed the quarry's Assembly Chamber 4L430 for an informal debriefing led by Captain Ascot. A UNSC flag was hung on the chamber's polycrete-coated walls, with portable standing lights and a folding conference table also set up for the debriefing. Along with Captain Ascot and Colonel Crowther, the meeting also included Lieutenant Commander Hector Nyeto of Ghost Flight, now-Captain Nelly Hamm, Avery Johnson, John-117, and Dr. Catherine Halsey. Here, they discussed the difficulties with the previous day's battle, particular those faced by Alpha Company. They had suffered a thirty-two percent casualty rate and lost their captain, while the rest of the battalion only saw a loss of six percent of their men and did not lose a single captain. After John's maverick action aboard the Ghost Song came up, the discussion turned to the young Spartan's age. Ultimately, the truth was revealed that John and his fellow Spartans were all around the age of fifteen, and Crowther refused to send them into battle again as a result. The conversation then turned to why the insurrectionists had seemingly been ready for their arrival, with John realizing and convincing the others that they had instead been waiting for the Covenant, with the intent to meet them for negotiations and to perhaps form an alliance. While they were planning for the Covenant's inevitable arrival, a flotilla of the alien ships appeared in-system and set course for Seoba. The other UNSC leaders then rushed out of the chamber to ready their forces for the imminent continuation of the battle, as Crowther remained where he was to talk with John. He assigned the Spartans to guard and load the captured insurrectionists into a transport as the Black Daggers mobilized to ambush the Covenant.

Only minutes later, most of the battalion had boarded the prowlers of Task Force Yama and launched from Seoba. Captain Ascot's and the other vessels of Night Flight had just received the last company of Black Daggers when the Covenant flotilla began bombarding the quarry. Ascot ordered the prowlers to launch immediately, but the Starry Night was struck on takeoff, causing it to crash into the quarry wall. Only Staff Sergeant Johnson and four Black Daggers survived the crash, and they were unable to radio their status to the rest of the task force. The ODSTs aboard the other prowlers of Night Flight were eager to search for survivors, but Colonel Crowther turned down their offer, not wanting to lose more men by sending them into the orbital bombardment. John-117 decided that he and his Spartans would check on the status of the Starry Night instead, once they finished their task of moving the prisoners. The Spartans ventured out into the ice quarry and reached the prowler to find a Covenant intrusion corvette securing it for recovery. Despite numerous setbacks, a team led by Frederic-104 managed to board the Starry Night, secure Johnson and the ODSTs, arm the vessel's nuke, and flee with the survivors in an escape pod.

Dispersal
After Operation: SILENT STORM, the remaining members of the battalion were dispersed to train other units. As a result, during Operation: OBLIVION, Admiral Cole didn't have anyone available to send with Blue Team and instead had to rely on regular infantry Marines.

Equipment
Due to the nature of their usual deployments, members of the 21st Space Assault Battalion are issued a space-assault variant of ODST armor, which is vacuum-sealed for use in extra-vehicluar operations in space, such as boarding actions. The armor is also shielded against the effects of electromagnetic pulses.

List of appearances

 * Halo: Silent Storm
 * Halo: Oblivion