The arquebus was used against enemies who were often partially or fully protected by steel-plate armor. Good suits of plate would usually stop an arquebus ball at long range. It was a common practice to "proof" (test) armor by firing a pistol or arquebus at a new breastplate. However, at close range, it was possible to pierce even heavy cavalry armor. This led to changes in armor usage, such as the three-quarter plate, and finally the retirement of plate armor from most types of infantry.