Dyer was born in Murree, in British India, now in Pakistan. He spent his childhood in Shimla and received his early education at the Bishop Cotton School in Shimla. He was born just six years after the Indian Rebellion of 1857. The rebellion was a war that had been fought by some Indians to end British rule. It had been defeated by the British but had created segregation, suspicion and fear between the British and the Indians. Although he had been born after the rebellion had ended, the effects had affected Dyer's life.