Historic Wall of Sirhind - Thanda Burj The year of 1704 was a traumatic period for the Sikhs when the four beloved sons of 10th Guru, Sri Guru Gobind Singh ji were losr forever. The two older sons attained martyrdom in the battle of Chamkaur on 22 and 23 December 1704, along with 3 Panj Piaras and 40 Mukte Sikhs laid down their lives fighting a massive Mughal army. The Chhotte Sahibzade [younger two sons of Guru Gobind Singh Ji] attained martyrdom on 26 December 1704 at a very young age of 9 & 7 years. This is known as Saka Sirhind . Imprisonment of Guru's Family Guru's mother Mata Gujari Ji with two younger grandsons, had taken refuge at the home of their family cook, Gangoo Pundit at his village, Saheri near Morinda. Gangoo betrayed the Guru's family by informing the Mughals about Guru's family. The three were arrested by the Morinda Kotwal and handed over to Wazir Khan, the Nawab of Sirhind. They were imprisoned, in the Thanda Burj (Open high Tower) in the icy