Lieutenant Chauncy is a one binome infected by Megabyte and is the chief commander of Megabyte's military. Lieutenant Chauncy led Megabyte's ABCs in several engagements, attacking the Principal Office, an uninfected sector of Giedi Prime, invading a nullified sector, and attacking Hexadecimal.
The Web invaded Mainframe when a Web portal opened above the city. Bob yelled to Megabyte to help the city's overwhelmed forces. Megabyte ordered Lieutenant Chauncy to have all his military in the air supporting the CPU's. Chauncy was extremely shocked at this, but quickly ordered every ABC into the air. This additional support helped to hold off the Web Creatures until the portal could be closed. After the portal to the Web was closed, Megabyte ordered Chauncy to destroy the remaining Web Creatures and then blow the CPU's out of the sky. (Web World Wars)
Under Chauncy's leadership the ABC's destroyed all but nine of the CPU's. With the remaining CPU's chased into the Principal Office the ABC's had the run of the city. Chauncy's new orders were to keep Enzo Matrix and AndrAIa from reaching the Game Cubes. This campaign was a failure for the most part, as Enzo made it to the Cubes all but one time due to Dot Matrix's plans.
The city eventually imprisoned Megabyte in Giedi Prime with a firewall. Megabyte forced Hexadecimal to open a rift in the firewall and had Lieutenant Chauncy lead the attack on the Principal Office. He met with greater firepower than he was able to cope with and turned back. Megabyte closed the rift to stop the weapon fire from getting through and Chauncy was deleted when his ABC hit the firewall. (Game Over)
After Mainframe crashed and was restored, all the deleted binomes were restored by back-ups. Lieutenant Chauncy was restored as well, and when the User ran a viral scan it disinfected all the binomes, including the Lieutenant. Once disinfected Chauncy, was revealed to have previously been an officer in the CPU defense force. (End Prog)
Chauncy didn't seem to do well in the CPU defense force as he was seen with a few other neo-virals at Al's Wait & Eat cafe. They were wearing what was left of their viral uniforms and Chauncy was wearing his commanders hat. They picked on the binomes there that were never viral.
Chauncy and Herr Doktor heard of Megabyte's return during Dot's wedding and organized a group of neo-virals to march at the Principal Office, calling for their return to viral. They were dispatched by the CPU guards.
Lieutenant Chauncy led a small group of ABC's in an attack at the Principal Office to steal the Gateway Command. They were successful and returned to a hideout on level 31. Lieutenant Chauncy and the viral guards watched out for an attack while Herr Doktor set up the Gateway. The Gateway turned out to be a fake, and the entire thing was a trap. The virals ended up in a firefight with a CPU squad, and lost. (Crouching Binome, Hidden Virus)
Lieutenant Chauncy is sometimes referred to as Commander by Megabyte. This could be because of his position as commander of his military, but he is publicly known as Lieutenant.