In ancient civilizations, the removal of the human penis was sometimes used to demonstrate superiority or dominance over an enemy. Armies were sometimes known to sever the penises of their enemies to count the dead, as well as for trophies. The practice of castration (removal of the testicles) sometimes involved the removal of all or part of the penis, generally with a tube inserted to keep the urethra open for urination. Castration has been used to create a class of servants or slaves called eunuchs in many different places and eras.