Marathon was a bar consisting of eight inches of braided chocolate and caramel. It was manufactured by Mars Inc and first sold in the United States in August 1973. The bright red packaging contained a ruler with inch markings on the reverse demonstrating that it was as long as it claimed. (The length was the result of its braided shape; it did not weigh more than standard candy bars.) It was discontinued in October 1981. Note: There was also a 15″ version of The Marathon Bar sold in Southern California at local 7/11 stores and at Michael’s Pharmacy in Swarthmore, Pennsylvania. These had the 15″ ruler on the back of the red wrapper.
Television commercials of the era feature John Wayne’s son Patrick as Marathon John who would regularly confront villain Quick Claude.
Another braided caramel and chocolate bar available from Cadbury is the Curly Wurly. While these are commonplace in their native UK (as well as Australia), aside from specialty import stores (andWorld Market) Curly Wurly bars are not widely available in the U.S.
Info gleaned from Wikipedia