Researching History: A Spent Bullet

Research Question
A rose by any other name is still a . . .

I’m starting a new manuscript tentatively titled, A Spent Bullet.

It takes place in SW Louisiana during the large La. Army Maneuvers of August 1941, and involves the evolving relationship between a young La. schoolteacher and a soldier from Wisconsin.

I’d appreciate reader input about what folks call “cold drinks” in different regions of the U.S.
Your names and details will help me.

Here is a short anecdote from that time.

A young boy, holding a coke and candy bar, was outside the local general store in his small town. He stood watching the endless procession of Army transport trucks passing by. (500,000 troops were in SW La. during this time.)

As the convoy stopped, a soldier called to him, “Hey, boy. I’ll give you a dollar for that cold drink and candy bar.”

The boy, who had paid 10 cents for both of them, gladly handled up his snack and took the dollar bill.

He was smart enough to realize he’d “found a bird nest on the ground.” He spent the rest of the day buying cokes and candy bars and turning a neat profit each time.

He took home more money that day than his sawmill-working daddy made in a week.

Here’s the question: What would soldiers from various parts of the U.S. call the “coke?”