used the outbreak of a major revolt in Persian Armenia in 571–572 as a pretext for refusing to prolong the payments. Justin's refusal was tantamount to a declaration of war, the fourth fought between the two great powers of Late Antiquity in the 6th century. After initial Persian successes such as the capture of Dara, the conflict proved inconclusive and became a drawn-out affair, with Byzantine victories followed by Persian successes, intermittent negotiations, and temporary truces. In 582, Maurice (r. 582–602), who had served as a general in the war, ascended to the Byzantine throne at Constantinople; by that time, the Persians had gained the upper hand in Mesopotamia through their capture of Dara in 574, while the Byzantines prevailed in Arzanene. Initial moves and dispositions Following the failure of another round of peace negotiations, about which little is known, Maurice appointed his brother-in-law Philippicus as the commander-in-chief for the Mesopotamian front (magister militum per Orientem) in 584. Philippicus raided the region around the major Persian fortress of Nisibis in 584, while in 585 he raided in Arzanene. The Persian commander, Kardarigan—"black hawk", an honorific title rather than a proper name—responded with an unsuccessful siege of Philippicus' main base, Monokarton. In spring 586 Maurice rejected new Persian proposals involving the conclusion of peace in exchange for renewed payments in gold. The contemporary historian Theophylact Simocatta reports that Philippicus' army was eager to confront the Persians in battle, and the Byzantine commander marched south from his base at Amida, crossed the Arzamon River (modern Zergan in south-east Turkey and north-east Syria) to its eastern bank and advanced some east to the plain of Solachon, where he pitched his camp. This position, south of the fortresses of Mardes and Dara, allowed Philippicus' army to control the passage of the Arzamon River and forced the Persian army under Kardarigan to advance across the waterless plain, away from their supply routes, before meeting the Byzantine force. On the Persian side, Kardarigan was also eager to fight and confident of victory. He arranged to be escorted by many camels carrying water for his troops in case the Byzantines refused to engage but continued to block access to the Arzamon, and had allegedly prepared iron bars and chains for the prisoners he would take. His movements, however, were detected when the Byzantines' Arab foederati captured a few of his men, allowing Philippicus to counter his forces.