Which Sikh Guru had all four of his sons killed by the Mughals?

Guru Gobind Singh had all four of his sons killed during conflicts with Mughal forces and authorities.

His two elder sons, Sahibzada Ajit Singh and Sahibzada Jujhar Singh, died fighting Mughal troops at the Battle of Chamkaur in December 1704. Ajit Singh was about 17 and Jujhar Singh about 13. They joined the battle despite the overwhelming size of the opposing army while their father escaped to continue leading the Sikh resistance.

The two younger sons, Sahibzada Zorawar Singh and Sahibzada Fateh Singh, were separated from Guru Gobind Singh during the escape from Anandpur. They were captured with their grandmother, Mata Gujri, and taken to Sirhind. The Mughal governor Wazir Khan ordered the boys executed after they refused to abandon their faith.

The four sons are collectively known as the Chaar Sahibzaade, meaning the four princes. A frequent mistake is saying all four died in one battle: the elder pair fell at Chamkaur, while the younger pair were executed at Sirhind. Their deaths became central to Sikh memory and martyrdom tradition.