>>528931718
Umas, even with their relative scarcity and their being women, most definitely would have had a place through the eras of centralized earshot command and formation fighting.

It wouldn't be until the era of artillery, mechanization and radios, and no doubt some form of 20th century social movement against the use of umas in war, that they would be given a general retirement of sorts like horses in our world. Modern umas would be relegated to all-volunteer specialist roles, at least in non-shitholes.