Just add seltzer to prune juice. Viola, Dr. Pepper!
It seems in WWII, sugar or corn sugar was rationed. Many soft drink companies were in trouble as a result.
Dr. P cleverly convinced the Govt.that if workers had one of their pops at 10am, 2pm and 6pm, their energy would stay high and they'd be more productive.
The pitch worked and they got all the sugar they needed.