ANSWER
When M&M's were first introduced in 1941 the original colors were red, yellow, green, brown, orange and violet. In 1949 tan replaced violet, and in 1995 blue replaced tan. Red disappeared in 1976, but reappeared in 1987.
As a few readers noted, when peanut M&M's were introduced in 1954 they only came in brown, with other colors being added a few years later.
M&M's were invented by Mars founder Forrest Mars Sr. They were based on a similar candy carried by soldiers during the Spanish Civil War, which were popular because the candy-encased chocolate would not melt. M&M's became very popular with American soldiers during World War Two for the same reason.
WHO GOT IT RIGHT: Marc Quinlivan, Marika Thiessen, Bob Milligan, and Joe Fischer.
