Fun fact
Bill's official description on the Wiki for L4D is
"It took two eventful tours in Vietnam, a handful of medals, a knee full of shrapnel, and an honorable discharge before the unthinkable happened: Bill ran out of wars. But now an army of infected has declared war on humanity. After decades of aimless drifting and dead-end jobs, Bill's finally gotten back the only thing he ever wanted: an enemy to fight."
The background of Bill is
It took two tours in Vietnam, a handful of medals, a knee full of shrapnel, and an honourable discharge to get William "Bill" Overbeck to stop fighting and try to live a peaceful life. He hated it. After decades spent drifting aimlessly through dead end jobs, Bill went in for a routine surgery and woke up to find the world he knew was gone. A plague was turning normal people into mindless killing machines. Naturally, the first thing he did was fight his way home and put on his uniform. Making his way through rural ghost towns and pitch-black forests, he found other Survivors, and together they fled from the infected hordes. In the end, Bill sacrificed himself to ensure their safety. His body was never found. Bill was left for dead. No one knows that he still has the only thing he ever wanted: an enemy to fight.
Here is a tip, the background for bill is actually a remade/extended version of is official description