He is named eventually Guru Teg Bahadur, which means brave sword or brave wielder of the sword, because as his father, Guru Hargobind, fought the Mughals, he was known as being unusually brave and an unusually competent warrior. He continued this tradition of being a warrior saint, and especially under the rule of Shah Jahan and Aurangzeb, as the Mughals became more and more intolerant and started forced conversions. He viewed himself as a protector of the oppressed, not just of the Sikhs, but the oppressed of any faith, including Hindus, who were being forced to convert by Aurangzeb. Eventually, Aurangzeb tortures and kills him for refusing to convert to Islam, and he is considered the second guru who is martyred. At his death, we have the 10th and last human guru of the Sikh tradition, Guru Gobind Singh, who continues, again, this tradition of a warrior saint, and actually formalizes it in this notion of Khalsa. There's a famous story of him gathering the Sikh community and asking for volunteers, and the first volunteer he takes into a tent, and then he emerges from that tent without the volunteer with a bloody sword, giving people the impression that he might have killed that individual. Then he asks for more volunteers, and more people come, and every time, he comes out of the tent without the volunteers, but with a bloody sword.