The Byzantine commander even lost his youngest son, Constantine, to Hamdanid captivity. Another expedition led by Bardas in the next year was also defeated, allowing Sayf al-Dawla to complete the re-fortification of Samosata and Hadath. The latter successfully withstood yet another Byzantine attack in 955. Sayf al-Dawla's victories brought about the replacement of Bardas by his eldest son, Nikephoros Phokas. Blessed with capable subordinates like his brother Leo and his nephew John Tzimiskes, Nikephoros would bring about a reversal of fortunes in Sayf al-Dawla's struggle with the Byzantines. The new domestic of the schools also benefited from the culmination of military reforms that created a more professional army. In spring 956, Sayf al-Dawla pre-empted Tzimiskes from a planned assault on Amida, and invaded Byzantine territory first. Tzimiskes then seized a pass in Sayf al-Dawla's rear, and attacked him during his return. The hard-fought battle, fought amidst torrential rainfall, resulted in a Muslim victory as Tzimiskes lost 4,000 men. At the same time, however, Leo Phokas invaded Syria and defeated and captured Sayf al-Dawla's cousin Abu'l-'Asha'ir, whom he had left behind in his stead. Later in the year, Sayf al-Dawla was obliged to go to Tarsus to help repel a raid by the Byzantine Cibyrrhaeot fleet. In 957, Nikephoros took and razed Hadath, but Sayf al-Dawla was unable to react as he discovered a conspiracy by some of his officers to surrender him to the Byzantines in exchange for money. Sayf al-Dawla executed 180 of his "ghilman" and mutilated over 200 others in retaliation. In the next spring, Tzimiskes invaded the Jazira, captured Dara, and scored a victory at Amida over an army of 10,000 led by one of Sayf al-Dawla's favourite lieutenants, the Circassian Nadja. Together with the "parakoimomenos" Basil Lekapenos, he then stormed Samosata, and even inflicted a heavy defeat on a relief army under Sayf al-Dawla himself. The Byzantines exploited Hamdanid weakness, and in 959 Leo Phokas led a raid as far as Cyrrhus, sacking several forts on their way.