You are correct. This happened long before WWI. And it was done by Robert-Houdin.
Actually it wasn't much of a war, but a fight. All these shaman people were doing all this VooDoo stuff. So they sent Robert-Houdin over to settle the nonsense in Algeria. So now he had 2 choices. . . expose them, or show them up. And he took the obvious path by showing him up.
He had an apple stuck on the end of a sword and said "fire at me and I'll catch it in the apple", they do and he catches it. The Shamans don't seem to care though. So he says to fire again, but before he grabs the sword, they fire, and BOOM, he catches it in his teeth. Now they were freaked.
But the trick that really stopped the war was the light and heavy chest. He said that he was so powerful that he could weaken even the most strongest/toughest men.
Robert-Houdin's performance of this and the alleged performance of the duel with the Marabout seemed to be the end of the rebellion. However, if you look at later history, it didn't stop the war. That war continued for a long time. Some feel that it is still going on.
Here's a link to an article on the subject by Teller.
http://query.nytimes.com/gst/fullpage.html?res=9D0DE6D81E39F93BA25757C0A96F958260
This information was obtained from various sources.