User blog comment:Jericho Henry135119/Which side do you prefer to be on during the Skyrim Civil War?/@comment-72.243.55.164-20120419020854/@comment-1840877-20120419192938

While the reason for your planned execution is never explicitly stated, it is implied that your character was trying to illegally cross the border into Skyrim. That and the captain present was just a bitch.