In the seventh and eighth century the Byzantine Empire was overwhelmed by Arab attacks resulting in the loss of Syria, Egypt and North Africa. The swift loss of the Empire’s lands and the continuous Arab sieges on Constantinople appeared to be signs of the end of the Byzantine Empire. In the late ninth and tenth centuries however this had changed, surprisingly within these centuries the Byzantine Empire experienced a period of revival. It was a period of increased trade and prosperity, a revival of the Empire’s economy. The Byzantine’s military had begun a process of transformation through new military tactics and reorganisation which made it a formidable fighting force. Simultaneously as these changes occurred, the Abbasid Caliphate had weakened significantly; a slave revolt and political divisions resulted in the split of the Abbasid Caliphate into three smaller Caliphates. The combined factors resulted in the expansion of the Byzantine Empire in the east in the late ninth and tenth centuries.
The most significant cause for this expansion was the army, specifically the use of new tactics and the reorganisation of the Byzantine army. The revival of the Byzantine economy was important as the increased trade and prosperity allowed greater taxation which could then be spent on the army for better weaponry and heavy Cavalry divisions. The revival of the economy is a contributing factor however it is subordinate to the army which was crucial. This is because the military success was stimulated to a greater degree by leadership and improved tactics rather than weaponry which was influenced by the revival of the economy. Without the introduction of new tactics and the reorganisation of the Byzantine army; the Byzantine Empire would not have been as successful in the expansion in the east. The decline and the splitting of the Abbasid Caliphate were contributing factors as the emerging Hamdanid Caliphate was weaker than its predecessor making it more exposable to attacks. This did not however mean the complete collapse of the Abbasid Caliphate. Its successor the Hamdanid Caliphate was still powerful, therefore it was the army reforms and new tactics which were the most significant reason in allowing the Byzantine to defeat the Arabs and make gains in the east.
The seventh and eighth centuries were periods characterised by the ‘Themes’. These were military districts with their own military governor and individual militia to defend each province in response to the new Arab threat. In the ninth and tenth centuries there was a shift in this policy. There was greater need for a military force for offensive assaults rather than defensive purposes. This resulted in the creation of the Tagmata, a paid, disciplined and highly trained army. The Byzantine army “evolved into a much more offensive tactical structure the main causes being the need to operate effectively on campaigns which demanded more than the seasonally available theme armies.” The shift from regional militias to a professional and well-disciplined army was crucial for the Byzantine Empires expansion in the east. It gave the Empire the ability to launch offensive campaigns; thereby allowing the Empire to make gains in the east which would not have been possible using the thematic militias as they were not suited to such warfare.
The introduction of new tactics and the reorganisation of the Byzantine army was a fundamental factor in the expansion in the east during the ninth and tenth centuries. Generals could utilise field manuals which produced “a flexible yet hard hitting force at their disposal that could respond appropriately to a range of different situations.” These field manuals also produced military drills to better prepare and improve the overall quality of their soldiers. The ‘De Velitatione’ is one example of these field manuals it states: