Ras Mengesha Yohannes was governor of Tigray and a son of Emperor Yohannes IV. His mother was Welette Tekle Haymanot wife of dejazmach Gugsa Mercha. Ras Araya Selassie Yohannes was his younger half brother. Prior to the Battle of Metemma, Mengesha Yohannes was considered to be a nephew of Emperor Yohannes IV. During the battle, the Emperor was mortally wounded and it was on his deathbed that Mengesha Yohannes was acknowledged as his "natural" son and designated as his heir. This created something of a succession problem.

Yohannes IV was Emperor of Ethiopia from 1871 to his death in 1889 at the Battle of Gallabat, and king of Tigray from 1869 to 1871. During his reign he successfully defended Ethiopia against a large-scale Egyptian invasion.