From the start of 40/660, Muawiya sent an expedition under the command of Busr bin Artat, to ravage the Hijaz. The main objective of this enterprise was to seize the important cities of Mecca and Medina, and so prepare the way for penetration into Yamen. Medina at this juncture, was governed by Ali's deputy, Abu Ayub Ansari, who at the approach of the Syrian invaders, could not offer any resistance, and fled from the capital. The entire city swore allegiance to Muawiya. Leaving Abu Hurrera to govern Medina, Busr bin Artat advanced to Mecca, which was at that time governed by Ibn Abbas. The inhabitants offered no resistence, and Ibn Abbas fled from the city. The Meccans like the Medinites, swore allegiance to Muawiya in a body.
From Hijaz, Busr went on through the southern parts of the Arabian peninsula until he reached the borders of Yamen. Ubaidullah bin Abbas, attempted to defend the province on Ali's behalf, but the small army which was all that he had been able to raise, was routed. At the approach of Busr, Ibn Abbas made a precipitate retreat, leaving the hazard of repelling the incursion to his deputy, Abdullah Harithi, who fought a pitched battle with Busr. Abdullah was defeated and killed. To oppose Busr in Yamen, Ali mustered 4000 men under the command of Jariah bin Kedaumah and Wauhib bin Masud, the Thaqafite from Kufa. It was now the turn to Busr to flee for his life. Scarcely had the Alid army reached the borders of Yamen, when Busr made his escape to Syria.
At this juncture, Egypt and Syria were under the occupation of Muawiya. In 40/660, Muawiya was however in Jerusalem, where he proclaimed himself the caliph of the Islamic empire. Ali was so staggered by Muawiya's claim of powers that he began to make huge preparations for an inroad on Syria, but in the interim, he had been assassinated in Kufa.