Both under saddle and in harness, breeching engages when an animal slows down or travels downhill and is used to brake or stabilize a load.
The breeching strap traces its roots back to the Chinese invented breast-strap or "breastcollar" harness developed during the Warring States (481–221 BC) era.
In a larger team, the leaders are in front of the shafts or pole and thus cannot slow the vehicle; nevertheless, they sometimes wear breeching for show.
Similarly, breeching and the requisite shafts or pole are not needed for a dragged load such as a plow or a log that will not move on its own, nor for a canal boat, which is towed by a long rope from the bank.
Historically, additional animals were sometimes used to brake very heavy vehicles on steep downhills, being hitched in harness breeching behind the load.
Mules often have lower withers and flatter backs than horses, making it likely that the saddle will slide forward when going downhill with a rider.