[1] Johnson was of a liberated African or recaptive family that was originally from Nigeria and was an Omoba of the Kingdom of Oyo as a descendant of Alaafin Abiodun.
In 1897 his older brother, the Reverend Samuel Johnson, completed a major work on the history of the Yorubas but, in Dr. Johnson's own words, "A singular misfortune...befell the original manuscripts of this history, in consequence of which the author never lived to see in print his more than 20 years of labour."
[1] In 1900, Johnson visited England and called on the publisher who told him he had misplaced the manuscripts and, "that they could not be found, and that he was prepared to pay for them."
Thus, Dr. Obadiah Johnson had "to rewrite the whole history anew from the copious notes and rough copies left behind by the author".
[4] He then acted as an unofficial adviser, as in 1903 when there was a crisis over the payment of the tolls that were collected from traders by native rulers, although Europeans were exempted.