How to Get “Equine Attack” Achievement & Trophy
The easiest method is to do this on the straw puppets (practice targets) at the Hidden Ones Bureau, at your settlement in England. To perform an assassination from a horse, you must tap [Crouch] while on the horse (this will make you stand on the horse). Then, press the button prompt that appears to perform the assassination. If you do not see the button prompt appear, try damaging the straw puppets a bit by kicking them from your horse. When they are low on “health,” the button prompt should appear. Since these practice targets do not move around, it is easier than doing it on real enemies.