Built in Sher Shah Suri's reign this gate was one of the entrances to the Pura Qila. Initially it was known as Kabuli Darwaza because of the caravans that came from that part of the country.
I thought it got its present name when Major Hodson murdered the sons of Bahadur Shah Zafar - Mirza Mughal and Mirza Khizr Sultan and grandson Mirza Abu Bakar, at the gate after the king's surrender to the British on September 22, 1857.
But apparently the name became popular during the Moghul days. Jahangir, ordered the killing of two sons of Abdur Rahim Khan-e-Khanan here on the charges of being traitors. Aurangzeb hanged the head of his elder brother Dara Shikoh at the gate after he ousted his father Shahjahan.
Wikipedia tells me that it is one of the 13 surviving gates of Delhi. 13?????? One trip to Chhattarpur and you can see bigger gates surviving !!!!