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According to The Ballad of Hamish Beamish, Beamish aspired to become a cadet at Corbulo Academy of Military Science at a young age, and embarked on a slipspace voyage to Circinius IV onboard the automated transport vessel UNSC Jamaica. However, his cryo chamber malfunctioned, causing him to be thawed out in the middle of the slipspace jump a decade before the ship was to arrive at its destination. With no spare cryotubes available and few resources at his disposal, Hamish kept himself warm by shaving and burning his own hair, and ate his own nails to avoid starving. Many years of such lonesome and gruelling existence left Hamish mentally disturbed. After ten years, the ship finally arrived at Circinius IV. Medics subsequently tried to rehabilitate Beamish, with little success. Finally, he was given the job of janitor at Corbulo Academy—the only work he was deemed suited for. Despite attaining short-lived fame, his story was eventually forgotten about by the academy's cadets. Much of these events are based on Hamish's own recounting and are unreliable due to his questionable sanity.
In 2526, Beamish was going about his duties as Corbulo Academy's janitor in the school's mess hall when a fight broke out between two freshman cadets, Thomas Lasky and Walter Vickers, with the former assaulting the latter as a response to verbal agitation by Vickers. Joining the crowd of spectators that quickly gathered around the brawl, Beamish froze in place and stared at the quarrel with a tense expression while firmly gripping his mop in a ready posture. He is believed to have died when the Covenant assaulted Corbulo Academy during the Battle of Circinius IV.
Beamish was awarded the "Golden Mop" award for his services at Corbulo Academy of Military Science.
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