Basil Crockett was born on in 1877 into a military family, the son of Edwin Arthur Brassey Crockett (1834–1915). Educated at Wellington, and Sandhurst, he commissioned into the 17th Lancers before attending Staff College in Poona, India. He served on the Northwest Frontier. Joining a Volunteer Battalion of the Gordon Highlanders during the Second South African War, he was awarded the Queen's South Africa Medal bearing the clasps for South Africa 1901, South Africa 1902, Orange Free State, Transvaal, and Cape Colony. Following the war he was commissioned a second lieutenant in a regular battalion of the Gordon Highlanders on 23 April 1902.