The siege lasted for several months, culminating in an Allied attack on the Italian garrison thereby forcing it to surrender. The Italians repelled them and they were forced to hold their positions along a nearby brook.
Almost no fighting took place in May as heavy rain bogged down the Belgians and turned their supply line from Sudan into mud, creating a food shortage. In early June, reinforcements arrived via river and the Belgians besieged the Italian supply depot at Mogi.
Aggressive patrols, combined with the actions of the Ethiopian resistance and raids from the South African Air Force put increased pressure upon the Italian garrison. At the end of the month General Auguste Gilliaert took charge of the Belgian force. He was instructed by the British to attack when an opportunity presented itself.
On 6 July, the Belgians formally accepted the surrender of Gazzera, eight of his generals and over 6, Italian soldiers. By 1 August, mobilisation in Italian East Africa had increased that number to , troops. In August , Wavell ordered a plan covertly to encourage a rebellion in the western Ethiopian province of Gojjam , which the Italians had never been able entirely to repress after the end of the Second Italo-Ethiopian War in May In September, Colonel Daniel Sandford arrived to run the project but until the Italian declaration of war, the conspiracy was held back by the British policy of appeasement, intended to avoid a simultaneous war with Germany and Italy.
Mission was formed to co-ordinate the activities of the Arbegnoch Amharic for Patriots. Sandford requested that supply routes to the area north of Lake Tana be established before the rains ended and that Selassie should return in October as a catalyst for the uprising. Gaining control of Gojjam required the Italian garrisons to be isolated along the main road from Bahrdar Giorgis south of Lake Tana , to Dangila , Debra Markos and Addis Ababa, to prevent them concentrating against the Arbegnoch.
