Stamina and Speed
Camels were the steed of choice when drudging through the African and Middle Eastern Fronts of the war. They could last a very long time without drinking water, travel fast at long distances, and carry a lot of payloads!
Camels were much smarter and more comfortable to control than horses once they were “barracked” or submitted to their handlers. They were also much calmer, too. Being a lot less prone to panic when exposed to enemy artillery and small arms fire, was a big plus in a war that saw tens of thousands of artillery rounds fired daily! But horses were given the brunt of the work during the Great War.