"Los Diablos Tejanos" - The Texas Devils. Empire of the Summer Moon goes deep into the orchestration, implementation, and efficacy of the Rangers against the Comanches and Apaches that had fought conventional army units to a standstill.
The above-mentioned Paterson and later Walker pistols, were originally scoffed at by the Army. The Rangers realized they needed the same capabilities to fight Indians from horseback and be able to travel for extraordinary lengths of distance. Revolvers gave them this capability and it changed the face of warfare forever. Comanches were so adept at using their mounted archers they could fire from under the neck of the horse at a full gallop and put dozens of arrows on target to a single musket ball in return, who also had to dismount to fire and reload. The new Walker pistols also had a faster reload, larger powder capacity, and much longer range. Combined with Comanche and Apache tactics, it was game over compared to a rider with just a bow and a lance or Mexican soldiers with cap & ball rifles. The first true "special forces", akin to what the SAS did in N.Africa.