Who is William Mandella from The Forever War and what is their importance?

William Mandella is the novel's main character. Mandella ranks in the top percentile of the world for intelligence, education, and physical fitness. As a result, he is included in the elite group of people conscripted into the united armed services of the world to battle the unknown and elusive Tauran aliens. Although this war spans over a millennium, Mandella unwittingly sees it through from beginning to end due to the time differential created by travel through constantly evolving wormholes. Over the period of the war, which spans 1,143 years, Mandella is promoted from private to sergeant to lieutenant and finally to major, commanding his own strike force.