The Amish train horses without violence. Fear makes a horse unpredictable. Trust makes it obedient.
Stages
0-6 mo: imprinting. Foal gets used to humans: touching legs, ears, muzzle. Lifting hooves. Leading on halter. 6-18 mo: voice commands: stop, walk, turn. Getting used to harness (no load). 18-24 mo: first light load: log, harrow. 24-36 mo: full load, working alongside an older horse. By 3 years — ready.
Principles
Repetition. Patience. Reward (oats, carrot, voice praise). Never strike. A horse that's been hit will work from fear — but will refuse at the most dangerous moment.
Voice Commands
Hü (go). Brrr (stop). Haw (left). Gee (right). Back. Whoa (slower). Same in all Amish communities — a neighbor's horse understands the same commands.