The only thing I come up with is the story of
Cyrus The Great of Persia's defeat of Croesus of Lydia (6th century BC):
"Cyrus is said to have overthrown the Lydians in the final battle by placing camels in front of his own troops, with the result that the strange smell so terrified the horses of the Lydian cavalry that their ranks were scattered in confusion."
To add: a painter named Harvey Dunn, in 1928, did a painting called
Fools, do you not know horses fear camels?
You've got my curiosity going though. Next time I'm at
our wonderful zoo, I'll ask one of the keepers. We're there about once a month.