Martyrdom is the supreme witness given to the truth of the faith: it means bearing witness even unto death. The martyr bears witness to Christ who died and rose, to whom he is united by charity. He bears witness to the truth of the faith and of Christian doctrine. He endures death through an act of fortitude. "Let me become the food of the beasts, through whom it will be given me to reach God."
Source: Catechism of the Catholic Church (Vatican.va)