He was raised by his maternal grandparents in North Battleford Saskatchewan, Canada,[2] after his parents' divorce when he was just a child.

For a few years he worked at the new plant in Chicago and supervised the development of the Snickers and 3 Musketeers bars.

[3] In 1934, he bought a British company, Chappel Bros, specialized in canned meat for dogs.

In partnership later with Bruce Murrie, Mars developed M&M's, the chocolate candy covered in a crunchy shell which "melts in your mouth, not in your hands," in 1940.

[10] Mars died at age 95 on July 1, 1999, in Miami, Florida, having amassed a fortune of $4 billion.

Forbes magazine ranked him as the 30th richest American (Forrest Jr. and John were 29th and 31st, respectively) and as the 103rd wealthiest person in the world.