Lost, rewritten, and then narrowly escaping destruction during WWI, his history has since become "the most frequently cited and most influential volume about the Yoruba-speaking people".

[1] Besides his historical contributions, Johnson led an active life, variously serving as a minister, teacher, and school superintendent in Ibadan, capital city of the Oyo state in Nigeria.

[4] He was later captured in the Atlantic Slave Trade but fortunately was rerouted to Sierra Leone, like many Yorubas, such as Samuel Ajayi Crowther (his distant cousin) and others.

Johnson declared that his chief aim in committing pen to paper was to safeguard the annals of Yoruba history, a heritage swiftly slipping into oblivion.

Thus, he wrote: "What led to this production was not a burning desire of the author to appear in print—as all who are well acquainted with him will readily admit—but a purely patriotic motive, that the history of our fatherland might not be lost in oblivion, especially as our old sires are fast dying out.

[10] In 1921, Obadiah finally succeeded in publishing the manuscript, titling the work The History of the Yorubas from the Earliest Times to the Beginning of the British Protectorate.

The editor [Obadiah] who was all along in collaboration with the author had occasion to visit England in 1900, and called on the publisher, but could get nothing more from him than that the manuscripts had been misplaced, that they could not be found, and that he was prepared to pay for them!