Johannes Theodorus van der Kemp was born in Rotterdam in 1747. He abandoned his studies in medicine at Leiden to join the army, serving in the Dutch dragoon guards until he resigned his commission in 1779. He then returned to medicine and completed his degree in two years at Edinburgh University. During his medical training he conducted experiments into asphyxiation, which involved the drowning of cats. He practised medicine in the Netherlands at Middelburg and near Dordrecht. On 27 June 1791 his wife, Christina, and daughter, Johanna, were both drowned in a yachting accident from which van der Kemp only narrowly escaped with his life. The loss brought about a religious conversion and he was inspired to undertake missionary work.
He contacted the London Missionary Society and was sent, at his suggestion, to South Africa as the leader of society’s first mission there. He sailed on the wretched, Australia-bound convict ship ‘Hillsborough’, arriving in March 1799. Van der Kemp travelled beyond the eastern boundary of the Cape Colony to work among the Xhosa, from whom he received the name Jank’hanna, or bald man. War between the Xhosa and Cape Colony forced his return west and he then worked, mainly with dispossessed Khoi-Khoi, founding a mission station at Bethelsdorp, near what was to become Port Elizabeth.
In 1806, he married Sara Janse, a formerly enslaved African woman some 45 years his junior, with whom he had four children. His attitudes and behaviour were met with considerable opposition among the white settler community of the colony. He was forced to leave the mission station and died of fever at Cape Town a few years later in December 1811.