to sue Mars for stealing the concept for Smarties and that after much negotiation, Harris and Forrest Mars Sr. agreed to share the marketplace rather than to compete, with Rowntree making Mars Bars in Canada, Ireland, and South Africa and with Mars making the sugar-coated confection in the United States without competition from Smarties.

The company's first big customer was the U.S. Army, which saw the invention as a way to allow soldiers to carry chocolate in tropical climates without it melting.