Arthur Lynch attained the rank of rear admiral in the Free Planets Alliance military. His earliest recorded command placed him over Alliance forces in the El Facil starzone during the 788 UC Battle of El Facil, where he attempted escape but was captured by Galactic Empire troops and imprisoned.

Years later, Lynch returned to the Alliance through a prisoner exchange arranged by Imperial leader Reinhard von Lohengramm. Secretly, Reinhard tasked Lynch with instigating a military coup against the Alliance government, promising him an Imperial rear admiralty in exchange. Lynch accepted, driven by personal vengeance against Alliance leaders he deemed hypocritical and self-righteous.

Collaborating with high-ranking officers like Admiral Dwight Greenhill, Lynch formed the National Salvation Military Council and executed the coup, overthrowing the civilian government. The coup collapsed under Admiral Yang Wen-li's counteractions. Facing defeat, Lynch disclosed to Greenhill and the council that Imperial manipulation had driven their rebellion.

Horrified, Greenhill attempted to shoot Lynch, but Lynch fired first, killing him. Other council members then executed Lynch and concealed his body to erase evidence of Imperial involvement. Lynch died in 797 UC. His coup directly ignited the Alliance Civil War, critically weakening the Free Planets Alliance in its war against the Galactic Empire.

Adaptations depict Lynch appearing increasingly haggard and disheveled after his imprisonment, mirroring his deteriorated mental state and obsessive focus on revenge.