The surrounding terrain was characterised by irregular heights, with flat or conical summits (ambas), intersected by deep ravines that were hardly traversable on foot.

One of them, Muntaz Unatù Endisciau, was captured by Ethiopian guerrillas, escaped, was mortally wounded while crossing a minefield and died after having his battalion's banner delivered to the Italian garrison.

After ascertaining the situation, the Carabinieri command decided to entrench its troops on the "Costone dei Roccioni", an overhanging ridge that dominated both the road to Gondar on the north and the Dessie–Debra Tabor side on the south (with the "Km.

Beginning on the end of August, Ethiopian irregulars started ambushes aimed at cutting communications and supply lines between Gondar and Culqualber.

On 4 September, some askari and blackshirt companies made a nocturnal sortie and attacked the Ethiopian encampment, capturing a large quantity of weapons and ammunition.

During September the Commonwealth forces, coming from south and readying for the attack, positioned themselves along the Guarnò river and on the Danguriè heights, directly threatening the "Km.

By then the Carabinieri defensive preparations were completed but the inflow of Commonwealth forces in the Gumera valley isolated the garrison of Culqualber from the rest of the Italian defence system, thus starting the siege.

At first the British forces tested the Italian defensive perimeter with patrol actions, then, after ascertaining the reaction, they advanced on the flanks, avoiding battle and encircling both Culqualber and Fercaber.

The encirclement of the Italians on Culqualber Pass was complete; their supply lines were cut off and they soon found themselves in hardships, having to ration their food stores; often the only meal consisted in bargutta, a gross flour obtained from corn, fodder and quadruped feed.

Carabinieri attempted to reach the rivers several times to retrieve some water but they became easy targets for the British fire, which caused heavy losses.

A method for obtaining small quantities of water consisted in spreading towels on the ground at night and retrieving them in the morning, when they were wet, thanks to high nocturnal humidity.

The sortie succeeded, allowing the Carabinieri, Zaptiè and the 4th Company of LXVII Colonial Battalion (Sub-Lieutenant Giovanni Pinat) to inflict heavy losses and to capture a considerable amount of weapons, ammunition and foodstuffs; exploiting their initial success, the Carabinieri and colonials then carried out a bayonet charge and overran the British defenders, which withdrew from Amba Mariam.

One of the two CR.42s, piloted by Sub-Lieutenant Ildebrando Malavolta, was engaged over Culqualber by two Gloster Gladiator and shot down by Lieutenant Lancelot Charles Henry Hope (3rd Squadron SAAF) on 24 October.

On 14 November the Allied attacks paused, and the Italians exploited this break to care for the wounded, bury the dead, and have their first hot meal in days.