Campaign against North Africa
After the withdrawal of 'Amr b Al 'Aas , when Abdullah b Sa'ad settled down as the Governor of Egypt, he sent raiding parties to the west. As a result of these raids the Muslims got considerable booty The success of these raids made Abdullah b Sa'ad feel that a regular campaign should be undertaken for the conquest of North Africa. North Africa was originally under Byzantine control, but after the withdrawal of the Byzantines from Egypt, North Africa had declared its independence under its king Gregory. The dominions of Gregory extended from the borders of Egypt to Morocco.
Jihad against North Africa
Abdullah b Sa'ad sought the permission of Uthman to undertake Jihad against North Africa. In Madina, Uthman summoned a meeting of the Majlis-i-Shura to consider the question. After discussion it was decided that a campaign against North Africa should be undertaken. It was also decided that a force from Madina should be sent to assist the Egyptian forces under Abdullah b Sa'ad. A force of 10,000 warriors was raised in Madina, and sent to Egypt under the command of Harith b Al Hakam, in the fall of 647 C.E. The Madina force included Ma'bad b Abbas; Abdul Rahman b Abu Bakr; Abdullah b Umar; Ubaidullah b Umar; Abdullah b Zubair; Abdullah b 'Amr Al 'Aas and Marwan b Al Hakam.
March to Tripoli
The Muslim forces assembled in Barqa in Cyrenica, the last outpost of the Muslims, and from there marched to Tripoli. The Muslims invested Tripoli. The siege lasted for some time' and ultimately the town fell to the Muslims.