William Underhill joined TRMN in September 2013. He languished in the personnel pool of HMSS Greenwich until 2015. During that time he rose in rank in a leisurely manner from Spacer 3/c to Petty Officer 3/c. In January he was transferred to HMS Truculent, where he struck for Power Tehcnician, becoming a Power Mate 3/c.
On February 28th, 2015, he was transferred to HMS Callisto as part of her commissioning crew, where he assumed the duties of Training & Records Petty Officer.
In March 2015, he transferred to the GSN and was assigned to the Isaiah Mackenzie Naval Academy in the post of NCO i/c Enlisted Training; this necessitated him being brevetted to Senior Master Chief Power Mate.
In June he was tapped to assume the post of Command SMCPO for TRMN's Bureau of Training.