The bar will be called Believe for a limited period as part of a £3.7m marketing investment base around the World Cup.
The Believe name will also be extended to Mars ice cream and drink.
Activity will include media partnerships with Talk Sport and The Sun, plus TV ads, press, radio and outdoor posters.
A dedicated website - www.marsbelieve.com - goes live on May 5 and the Believemobile will visit nine UK cities on its way to Berlin.
While the main focus for advertising the bar in England will be on the national team, in Scotland, Wales and Northern Ireland a generic World Cup campaign will run.
Believe products are available in cash and carries now to retail on April 24. The limited-editions will begin to be phased out in the same week that England play their first game on June 20, to minimise the risk of leftover stock should England be knocked out.
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