The Battle of Ajnadayn () was fought in July or August 634 (Jumada I or II, 13 AH), in a location close to Beit Guvrin in present-day Israel; it was the first major pitched battle between the Byzantine (Roman) Empire and the army of the Arab Rashidun Caliphate. The result of the battle was a decisive Muslim victory. The details of this battle are mostly known through Muslim sources, such as the ninth-century historian al-Waqidi. Sources Regarding the primary sources, there is an absence of any of Byzantine provenance; possibly, according to Walter Kaegi, because what Byzantine material exists may conflate the battle with other Byzantine defeats, such as Dathin and Yarmouk. The earliest source appears to be an entry in the Frankish Chronicle of Fredegar, compiled in 658-660, unless this is a possible interpolation. Background According to David Nicolle, the Rashidun army left the capital Medina probably in the autumn of 633, but possibly at the beginning of 634. They first engaged and defeated the Byzantines at Dathin on February 4; after that Emperor Heraclius, then stationed in Emesa, had reinforcements sent south to protect Caesarea Maritima. As a possible reaction, commander Khalid ibn al-Walid was ordered to interrupt operations against the Sassanian Empire and reach Syria, which brought him to engage and defeat the Byzantine-allied Ghassanids by April 24, permitting him to enter almost unopposed in Bosra. At this point, Khalid converged with several armies, led by generals such as Abu Ubaydah ibn al-Jarrah, Yazid ibn Abi Sufyan, Amr ibn al-As and Shurahbil ibn Hasana. Khalid united with Amr's forces in a place known traditionally as Ajnadayn. The site is placed by the Muslim literary sources somewhere between Ramla and Bayt Jibrin (modern Beit Guvrin), both in modern Israel, but is otherwise unattested by any geographer of the period. Based on the region's topography, the historian N. A. Miednikoff suggested that the battle was fought on the Wadi al-Samt river (Valley of Elah), where lies the twin village of al-Jannaba. According to the hypothesis advanced by Miednikoff and Michael Jan de Goeje and summarized by Leone Caetani, it was from the dual form (al-Jannabatayn) of the village the historical name of the battle emerged, by conflation with the plural for "army", ajnad. Opposing forces Regarding the strength of the confronting armies, H. A. R. Gibb in the Encyclopaedia of Islam argues that, at best, both forces were made