1) Scientists at a nearby laboratory reported that their zombie experiment went wrong, causing a huge zombie outbreak that is rapidly spreading towards Fort Dawn and the surrounding region.
2) The zombie outbreak started that morning and is now only 10 miles away, heading directly for Fort Dawn. It is growing larger, faster, and more aggressive.
3) With communications down and a scout missing, General Marshall warns the soldiers at Fort Dawn to arm themselves as they may be the last line of defense against the zombie outbreak reaching them within the hour.