The attack was part of Operation Unokat which aimed to break the roadblocks set up by the gendarmerie by the end of November 1961 and at the same time stop Katangese President Moïse Tshombe's opposition to the UN.

In a coordinated offensive, Swedish troops captured Camp Massart; Irish troops attacked the railway tunnel; the Indian contingent created diversionary attacks and blocked fleeing Katangese forces; and the Ethiopian forces secured the western part of the city.

[9] The advance began and an extraordinarily strong tropical downpour filled in a few minutes the Kapemba stream which became a rushing river.

The advance party got with difficulty wading across; a machine-gun squad moved the heavy Kulspruta m/42 machine gun across using a floating door.

The advance took place under heavy enemy fire from mortars and machine guns, and from snipers in the buildings' upper floors.

Some houses got cleaned out using armor piercing explosive shells, fired by Carl Gustaf 8.4cm recoilless rifle gunner Andersson from Skövde.

[1] By 08.30[1] the distance was close enough, 30 meters from the Camp Massart's main entrance, which was partially blocked, for the Swedes to make a charge.

[7] The advance party (Gullstrand) secured the flanks with two machine guns and 3rd Company's 2nd Platoon (Kamstedt) stormed into the big military base.

The attack was directed against the Swedes' left flank and was supported by fire from the surrounding houses inhabited by European employees of the Katangan railway company BCK.

At 1 pm, the UN headquarters announced that the Swedes had definitely captured the area around the main entrance but that it would take the whole day would to clear the rest of Camp Massart.

On 18 December Secretary-General U Thant declared a unilateral ‘temporary ceasefire’[6] and Tshombe began to negotiate with the central government.