Rapid Fire (A Gatling Western #7‪)‬

At the end of the Civil War, General Jackson Kilby took some of his fellow Confederates south to settle in a new land: Parimba Province, Brazil. There they prospered, and were continuing to prosper when Jorge Suarez, a violent revolutionary and his army of murderers and maniacs, threatened their continued survival.

The old general was a fighter. But to fight Suarez he needed guns. So he bought eighty thousand dollars' worth of weapons and ammunition from the Maxim Firearms Company, and Maxim's representative, Gatling, was sent along to make sure they arrived safely and that Kilby's men knew how to use them. Gatling had no intention of fighting the war himself. But Fate had other ideas about that. And that's why the Amazon started running red pretty soon after he got there.