in 1956, two WWII Navy vet brothers launched Mister Softee, and the ice cream trucks were part of the Civil Defense network during the Cold War

The trucks carried a generator, potable water, freezer, refrigerator, loudspeaker and two floodlights that could be used to provide aid to communities suffering in the aftermath of an attack.

https://www.facebook.com/NavalInstitute/posts/495755918879670

Around 1999, their sons took over the business.

The new ice cream brand was launched to the public in West Philadelphia on St Patrick's Day 1956, and then later that year at The National Ice Cream Convention in Atlantic City.

By 1968 Mister Softee vans were operating in 15 countries from Belgium to Australia.

In the 70s, the competition from grocery stores started the decline of the profits in roaming ice cream sales. 

Recently, Mister Softee was named as one of the highest exposed brands in the latest Marvel movie Captain America: Civil War. In a memory-based virtual reality simulation projected at M.I.T., a young Tony Stark dons a Mister Softee shirt in his childhood home while talking to his parents.

https://mashable.com/feature/history-of-mister-softee