extended their conquests if Carus had not died in December of the same year. His successor Numerian was forced by his own army to retreat, being frightened by the belief that Carus had died of a strike of lightning. After a brief period of peace during Diocletian's early reign, Narseh renewed hostilities with the Romans invading Armenia, and defeated Galerius not far from Carrhae in 296 or 297. However, in 298 Galerius defeated Narseh at the Battle of Satala, sacked the capital Ctesiphon and captured the Persian treasury and royal harem. The resulting peace settlement gave the Romans control of the area between the Tigris and the Greater Zab. The Roman victory was the most decisive for many decades: all the territories that had been lost, all the debatable lands, and control of Armenia lay in Roman hands.Many cities east of the Tigris were given to the Romans including Tigranokert, Saird, Martyropolis, Balalesa, Moxos, Daudia, and Arzan. Also, control of Armenia was given to the Romans. The arrangements of 299 lasted until the mid-330s, when Shapur II began a series of offensives against the Romans. Despite a string of victories in battle, culminating in the overthrow of a Roman army led by Constantius II at Singara (348), his campaigns achieved little lasting effect: three Persian sieges of Nisibis, in that age known as the key to Mesopotamia, were repulsed, and while Shapur succeeded in 359 in successfully laying siege to Amida and taking Singara, both cities were soon regained by the Romans. Following a lull during the 350s while Shapur fought off nomad attacks on Persia's eastern and then northern frontiers, he launched a new campaign in 359 with the aid of the eastern tribes which he had meanwhile defeated, and after a difficult siege again captured Amida (359). In the following year he captured Bezabde and Singara, and repelled the counter-attack of Constantius II. But the enormous cost of these victories weakened him, and he was soon deserted by his barbarian allies, leaving him vulnerable to the major offensive in 363 by the Roman Emperor Julian, who advanced down the Euphrates to Ctesiphon with a major army. Despite a tactical victory at the Battle of Ctesiphon before the walls Julian was unable to take the Persian capital or advance any farther and retreated along the Tigris. Harried by the Persians, Julian was killed in the Battle of Samarra, during