In August 1888, Slessor travelled north to Okoyong, an area where male missionaries had been killed.
She thought her teachings, and the fact she was a woman, would be less threatening to unreached tribes.
For 15 years, Slessor lived with the Okoyong and the Efik people.
She learned to speak the native Efik language, and made close personal friendships wherever she went, becoming known for her pragmatism and humour.
Slessor lived a simple life in a traditional house with Efiks.
Her insistence on lone stations often led her into conflict with the authorities and gained her a reputation for eccentricity.
However, her exploits were heralded in Britain and she became known as the "white queen of Okoyong".
Slessor continued her focus on evangelism, settling disputes, encouraging trade, establishing social changes and introducing Western education.

It was the belief in the area that the birth of twins was considered a particularly evil curse.
Natives feared that the father of one of the infants was a 'devil child', and that the mother had been guilty of a great sin.
Unable to determine which twin was fathered by the evil spirit, the natives often abandoned both babies in clay pots to die.
In most of Calabar the practice had been eliminated by the Missionaries and King Eyo Honesty II.
Slessor left the area of Calabar and moved further in to Okoyong.
She adopted every child she found abandoned, and sent out twins' missioners to find, protect and care for them at the Mission House.
Some mission compounds were alive with babies.
Slessor once saved a pair of twins, a boy and a girl, but the boy did not survive.
Mary took the girl as her daughter and called her Janie.
She took Janie home to Scotland with her on at least one visit.

In 1892, Slessor became vice-consul in Okoyong, presiding over the native court.
In 1905 she was named vice-president of Ikot Obong native court.
In 1913, she was awarded the Order of St John.
Slessor's health began to suffer in her later years, but she remained in Calabar, where she died in 1915.
In August 1888, Slessor travelled north to Okoyong, an area where male missionaries had been killed. She thought her teachings, and the fact she was a woman, would be less threatening to unreached tribes. For 15 years, Slessor lived with the Okoyong and the Efik people. She learned to speak the native Efik language, and made close personal friendships wherever she went, becoming known for her pragmatism and humour. Slessor lived a simple life in a traditional house with Efiks. Her insistence on lone stations often led her into conflict with the authorities and gained her a reputation for eccentricity. However, her exploits were heralded in Britain and she became known as the "white queen of Okoyong". Slessor continued her focus on evangelism, settling disputes, encouraging trade, establishing social changes and introducing Western education.
It was the belief in the area that the birth of twins was considered a particularly evil curse. Natives feared that the father of one of the infants was a 'devil child', and that the mother had been guilty of a great sin. Unable to determine which twin was fathered by the evil spirit, the natives often abandoned both babies in clay pots to die. In most of Calabar the practice had been eliminated by the Missionaries and King Eyo Honesty II. Slessor left the area of Calabar and moved further in to Okoyong. She adopted every child she found abandoned, and sent out twins' missioners to find, protect and care for them at the Mission House. Some mission compounds were alive with babies. Slessor once saved a pair of twins, a boy and a girl, but the boy did not survive. Mary took the girl as her daughter and called her Janie. She took Janie home to Scotland with her on at least one visit.
In 1892, Slessor became vice-consul in Okoyong, presiding over the native court. In 1905 she was named vice-president of Ikot Obong native court. In 1913, she was awarded the Order of St John. Slessor's health began to suffer in her later years, but she remained in Calabar, where she died in 1915.
Mary Slessor