The Battle of Debre Abbay was a conflict between Ras Marye of Yejju (Oromo rulers of abyssinia) Regent of the Emperor of Ethiopia, and his rival from Tigray, Dejazmach Sabagadis of Agame. Although Ras Marye lost his life in this battle, Dejazmach Sabagadis was defeated, and after surrendering was executed by Ras Marye's Oromo followers.
Ras Marye had inherited the mantle of Regent of the Emperor of Ethiopia, and while admittedly a Christian, his Oromo ancestry caused much resentment from the other Christian aristocrats and nobles of Ethiopia. Dejazmach Sabagadis attempted to exploit this antipathy, and succeeded in forming a coalition with his fellow Christian lords of Gojjam, Lasta and Semien against Ras Marye.
Forewarned of this plot, Ras Marye struck first and defeated the members of this coalition individually. After defeating Dejazmach Goshu in Gojjam, Ras Marye turned north and marched into Semien and attacked Dejazmach Wube Haile Maryam; Sabagadis failed to come to the help of his ally, and Wube decided to submit to the Ras than face him alone. Having isolated Sebagadis, Ras Marye now crossed the Tekezé River against his rival, supported not only by Oromo contingents from Wollo, Yejju, Begemder and Amhara but also by the armies of Dejazmaches Wube and Goshu.
The opposing armies met on 14 February 1831 at Mai Islami near Debre Abbay (which is why this battle is also sometimes called the Battle of Mai Islami). Although Sabagadis had the superiority of a far larger number of firearms, his matchlockmen were poorly employed and failed to overcome the vaunted Oromo cavalry. The battle resulted in immense casualties, one of whom was Ras Marye. Defeated, the Dejazmach sought to escape the vengeance of Ras Marye's kinsmen by surrendering to his former ally Wube; Wube handed the Dejazmach over to his victorious allies, and the Oromo executed Sebagadis.
The Oromo ravaged Tigray under their new chief, Ras Dori of Yejju, but withdrew to Begemder due to his increasing illness before his death. In the chaos that followed Sabagadis' death, Wube emerged as the primary warlord of Tigray.
