It is hard to overestimate how important this battle was.
You can read an account of it here. Some 15,000 Eritrean fighters under Mesfin Hagos took on a much larger Ethiopian force (20,000 – 22,000 Ethiopian troops, with Soviet advisers) armed with tanks, heavy artillery and with cover from the Ethiopian air force.
Despite these advantages, the Eritreans fighters managed to block the convoy in the narrow valley, trapping them and wiping them out.
This assessment was provided by Berhane Woldemichael in the periodical Review of African Political Economy.
“The significance to the Ethiopian regime of the loss of Afabet cannot be overstated. In this single battle, Ethiopia lost whole divisions of its best trained and armed troops. Worse still, it left behind a weapons stockpile that it had amassed to carry out what it believed was to have been ‘a decisive offensive’ against the EPLF. That ‘decisive offensive’ was being planned by Soviet military advisors. As it was, the EPLF, clearly outsmarting the Soviets, turned around the ‘planned offensive’ to their advantage. The Soviet Union had always denied direct involvement in Eritrea but was caught red-handed by the EPLF at Afabet by the capture of three Soviet military personnel, another one was killed in the combat.”
I saw the ruined tanks, and rusting guns when I visited the area. The photograph above is by David Stewart-Smith and is dated 12/1989
It’s caption reads: “Town of Alfebet [sic.] captured in March 88, major victory of the EPLF – destroyed tanks, vehicles, etc.”