During World War I, Burnett joined the Navy for six months. His service was mostly at Great Lakes building a breakwater. After the USN, Burnett returned to Cadillac. A few employees at Cadillac formed the LaFayette Motors Company – triggering Burnett to move to Indianapolis to work for the new firm. Soon he was offered a position with Homer McKee. He then left LaFayette and joined McKee, where Burnett said of the founder, "(He) gave me my first feel of what I have come to regard as the "warm sell" as contrasted to the "hard sell" and "soft sell". This was his first agency job.