Originally a TIE fighter pilot for the Vast Empire Navy, he quickly earned the handle 'Cartwheel' for his favorite maneuvers. Peter McCarthy has an attitude that frequently gets him in trouble with superiors, which explains how he was assigned as a pilot to the Stormtrooper Corps. The Navy did not desire him very much, but did not have the necessary grounds to discharge him; and the Army required pilots to fly the squads into action. Naturally the Navy assigned their least favorite pilot to the Army.

Extremely skilled, his rank suggests a far lower talent and experience than he actually has. McCarthy, assigned to Eclipse Squad at this time, is greatly satisfying the Stormtroopers that are thrill seekers when he pilots their shuttles. Those that don't appreciate a beautiful, perfectly executed triple-dive with a 720 degree barrel roll and reverse tail flip in a standard Imperial Shuttle generally don't complain because their mouths are busy expelling their last meal.