Aurangzeb decided to Islamize India as fast as possible, starting with Kashmir. He had a devil's brain and he devised all kinds of artifices to get his way. Writes Sir Jadu Nath Sarkar in his renowned five volume History of Aurangzeb: "In Kashmir, Hindus and Muslims used to intermarry, and the wife, whatever might have been her father's creed, was cremated or buried as her husband happened to be a Hindu or Islamite. But in October, 1634, Shah Jahan forbade the custom and ordered that every Hindu who had taken a Muslim wife must either embrace Islam and be married anew to her, or he must give her up to be wedded to a Muslim. This order was rigorously enforced."
The rise was to turn the Hindus into Muslims by virtue of political power. In any event, it was still a 'slow' process from Aurangzeb's point of view. He wanted to turn the world into a Koranic world of Muslims only and those who still did not opt for Islam, had no place in the kingdom.
'Aurangzeb ordered that every Hindu must become a Muslim under pain of death. The Hindus wanted a period of six months to consider the proposal, which was granted. Aurangzeb also issued a fiat that those who refused to be Mohammedans would be put to the sword and a wholesale order was issued to kill the Brahmins and collect their janoys or sacred threads, as proof of the slaughter.
Naturally, the Guru was plunged into deep thought. He noticed the sad faces of the Brahmins. His young eight-year-old son, Govind Rai (the future Guru Gobind Singh) asked his father why these good men looked so worried? What has happened!
Continuing the rest of the story from a different source
Guru ji slowly turn to his son and explain the situation as concisely as possible.
"Baata (Son), this is sangat from Kashmir. They are Hindus who have been friends of Sikhs since the time of Guru Nanak. They have a very serious problem on their hands" said Guru ji.
Gobind Rai replied, "Pita ji, you are the Guru of the entire world ("Jagat Guru"). You will know of a solution to all problems"
In the summer of 1675, the Guru, along with some of his companions were finally brought to Delhi and asked to convert to Islam or else face the penalty of death. Guru ji was also asked to perform a miracle. Guru Tegh Bahadur averred that he would rather sacrifice his life than give up his faith and his freedom or belief or perform a miracle. Thus, under Aurangzeb's orders, Guru ji and his companions were tortured. The Guru was chained and imprisoned in a cage and was tortured in the cruellest and the most inhuman ways for five long days. In order to terrorise him further into submission, one of his distinguished devotees (Bhai Mati Das) was sawn alive, another (Bhai Dyal Das) was boiled in the cauldron and the third (Bhai Sati Das) was roasted alive before the Guru.
Finally, the Guru himself was beheaded, under imperial warrant, in broad daylight, in the middle of a public square, the most prominent public place in India, called Chandni Chowk, of Delhi, on the charge that he was a stumbling block preventing the spread of Islam in the Indian subcontinent. The exact location of the beheading is marked by Gurdwara Sis Ganj in Delhi. His martyrdom was yet another challenge to the Sikh conscience. It was then realized that there could be no understanding between an insensate power imbrued with blood and a proud people wedded to a life of peace with honour. The sacrifice roused the Hindus from their passive silence and gave them the fortitude to understand the power that comes from self-respect and sacrifice. Guru Tegh Bahadur thus earned the affectionate title of "Hind-di-Chadar" or the Shield of India.