Forrest Mars and the Mars bar

The Mars bar feels as British as a red post box. It was invented by an American, in a small factory in Slough, after a blazing row with his father.

A boy who barely knew his father

Forrest Edward Mars was born on 21 March 1904 in Wadena, Minnesota, the only child of Frank Mars and his first wife, Ethel. His parents divorced when he was small, and he was brought up by his grandparents in North Battleford, Saskatchewan, in Canada. He rarely saw his father. He studied at the University of California, Berkeley, then at Yale, where he took a degree in industrial engineering in 1928.

Into the family firm, and out again

In 1929 Forrest joined his father's company, the year it moved to Chicago. He worked on the development of the Snickers and 3 Musketeers bars, and he always claimed that the Milky Way, his father's first big hit, had been his idea, after drinking a malted milkshake.

Father and son soon clashed. Forrest wanted to take the business abroad; Frank did not. After a quarrel, Forrest was removed from the company. He left with a $50,000 payment and the foreign rights to the Milky Way.

Slough, 1932

Forrest went to Europe and worked briefly for Nestlé and for Tobler, the Swiss chocolate maker. Then, in 1932, he set up his own company, Mars Limited, on the new Slough Trading Estate in Berkshire. With a staff of twelve he made the first Mars bar: nougat and caramel covered in milk chocolate, based on the Milky Way but adjusted for European tastes. Early advertising said it used Cadbury's chocolate.

It was a hit. Four years later he created Maltesers at the same factory, launched in 1937 and sold at first as energy balls for women watching their weight. In 1934 he had also bought a British maker of canned dog meat, Chappel Brothers, and launched Chappie. That was the start of a pet food business that grew into Pedigree and Whiskas.

Back to America

During the Second World War Forrest lived in the United States. In 1941 he launched M&M's with Bruce Murrie, son of the president of Hershey, and the two Ms stand for their surnames. The idea may have come from Smarties, which Forrest is said to have seen soldiers eating during the Spanish Civil War: see how Smarties inspired M&M's. Peanut M&M's followed in 1954, which Forrest helped to develop even though he was allergic to peanuts.

Winning the family firm

Frank Mars died in 1934. Thirty years later, in 1964, Forrest won control of his late father's company and merged it with his own. He ran Mars in his own way: strictly private, with staff forbidden to talk to the press. He retired in 1973 and handed the business to his children, then started a luxury chocolate company, Ethel M, named after his mother. He died in Miami on 1 July 1999, aged 95. The story of the family he left behind is in the mystery of the Mars family.

The Mars bar today

The Mars bar is still made to much the same idea: nougat and caramel in milk chocolate, in the black wrapper with red and gold lettering. Three million of them went with the British task force to the Falklands in 1982. It has got smaller, though. In the UK the standard bar went from 62.5 g to 58 g in 2008, when Mars first said the change was to help tackle obesity and later admitted the real reason was rising costs. It dropped to 51 g in 2013 and to 40 g in 2026. More in shrinkflation.

Mars still has its UK headquarters in Slough, where it all began.

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