It was, therefore, now Muâvia’s opportunity for asserting his title to the whole Moslem empire. Already, in accordance with Amru’s verdict at the Arbitration, he was recognised as Caliph throughout Syria and Egypt.[570] Resenting the succession of Hasan to his father’s power at Kûfa, Muâvia at once gathered a powerful army and marched to invade Irâc. No sooner was this intelligence received, than the men of Kûfa, impatient at the prospect of falling under the rule of Syria, rallied beneath their new Caliph’s standard, and an army forty thousand strong was ready to repel the attack.[571] But Hasan had no stomach for the war. Sending forward his vanguard of twelve thousand men under the brave and faithful Cays, he followed himself irresolutely; and, with the bulk of his army, rested at Medâin amidst the luxurious gardens of the old Persian Court.[572] While thus ignobly holding back, the report gained currency at Medâin that Cays had been defeated on the plains of Mesopotamia, and slain. An émeute ensued. The troops rose mutinously upon the Caliph. They rushed into his sumptuous pavilion, and plundered the royal tents even to the carpets. A project was set on foot to seize his person, and, by delivering him up to Muâvia, thus make favourable terms. The faint-hearted Caliph, alarmed at these demonstrations, took refuge in the Great White Palace, a more congenial residence for him than the martial camp; and, trusting no longer to his fickle and disloyal people, sent letters to Muâvia offering to submit. [Sidenote: abdicates in favour of Muâvia July, A.D. 661.]Hasan agreed to abdicate and retire to Medîna, on condition that he should retain the contents of the treasury, five million pieces; that he should receive for his support the revenues of a Persian district; and further, that the imprecation against his father should be dropped from the public prayers. Muâvia granted the first two requests; and as for the third, he consented that no prayer against Aly should be recited within hearing of his son. The truce was ratified accordingly on the 24th day of Rabî I. After a brief and inglorious reign of only five or six months, Hasan, with his household and belongings, retired to the Hejâz. The people of Kûfa, we are told, wept at their departure. But Hasan left them without regret. It was a race, he said, in whom no trust could be reposed, and who had set purpose neither for good nor for evil.[573] [Sidenote: Cays submits to Muâvia.] Cays, whose ability and prowess were worthy of a better cause, remained for some little while longer in the field. But at length, having obtained terms for all his soldiers who had been fighting on the side of Aly, and there being no longer any master left to fight for, he laid down his arms and recognised Muâvia as supreme.[574] [Sidenote: Muâvia sole and undisputed Caliph.]