In ancient civilizations, removal of the human penis was sometimes used as a means of demonstrating superiority: armies were sometimes known to sever the penises of their enemies to count the dead, as well as for trophies, although usually only the foreskins were taken. The practice of castration (removal of the testicles) sometimes also involves 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 (and especially harem-keepers) called eunuchs (Greek Ευνούχοι) in many different places and eras.