During the first weeks of January, Ras Cassa, Ras Sejoum, Ras Mulughietà and Ras Immirù (fielding a force of over 150,000 regulars and irregulars between them) conceived a daring plan to destroy Marshal Badoglio’s forces near Adowa, followed up by an assault on Eritrean territory. However, across a front of least 200 kilometers, it was too ambitious a plan for four corps-sized masses with little radio communications, no air cover, and a significant level of rivalry among the Rases. Alerted by aerial reconnaissance and some minor engagements, Badoglio moved quickly and attacked the Ethiopians first. Thus began the First Battle of Tembien.

The Eritreans and Ethiopians fought a tenacious battle all day, and possession of the Mehenò village passed back and forth several times amid intense hand-to-hand fighting. By the mid-afternoon, however, the Italian-led troops had managed to clear the Zeban Kerkatà Hills of enemy forces, from which the obstinate but uncoordinated attacks had launched. This strong Ethiopian detachment failed its objective of infiltrating between two of the Italian corps, while another detachment in the same region was also identified and severely beaten by another Italian column. In fact, the other detachment was so damaged by preparatory artillery and machine-gun fire that rifle fire was not needed to break the force. To add insult to injury, Ras Cassa possessed one of the few radio sets in the field, and after this battle called the Emperor to admit his defeat, only to have the Italians intercept and listen in on the radio transmission. For the Italians, the First Tembien battle seemed an auspicious beginning.