Guru Gobind Singh's wars with the Mughal empire and the hill states cost him his entire immediate family within the span of a single winter. In December 1704, after the Mughal army broke a truce and besieged Anandpur, his two elder sons, Ajit Singh and Jujhar Singh, were killed fighting at the battle of Chamkaur, while his two younger sons, Zorawar Singh and Fateh Singh, were captured with their grandmother, taken to Sirhind, and executed on the orders of the local Mughal governor after they refused to renounce their faith. Sikh tradition remembers all four as the Chaar Sahibzade, the four sons, and their deaths are commemorated every year, the younger boys' martyrdom especially, as a defining act of witness in Sikh memory.
In the aftermath, Guru Gobind Singh wrote a letter in Persian verse to the emperor Aurangzeb himself, the Zafarnama, Letter of Victory, rebuking him for breaking his oath and for the killing of the Guru's sons while asserting that ultimate victory belonged to truth rather than to imperial power. The letter is preserved as part of the Dasam Granth tradition and stands as a rare direct address from a Sikh Guru to a reigning Mughal emperor, a documented historical exchange rather than only a devotional legend.