History of Wars Summary 21 - Arab-Eastern Roman War 2: Arab Advance Towards Syria

Immediately after Heraclius concluded his war with Persia, the Arab invasion began. Under the rule of Caliphs Abu Bakr and Umar, the Islamic forces rapidly advanced beyond the Arabian Peninsula into Syria and Palestine. The Eastern Roman army resisted using border fortresses, but they were short on troops in many areas, and some local residents were dissatisfied with the central government's high taxes and religious policies. The defeat of the Eastern Roman army at the Battle of Ajnadayn in 634 shook the defenses of Syria, and the Battle of Yarmouk in 636 became a decisive turning point. Although the Eastern Roman army deployed a large force, they were defeated by the mobility and command of the Arab army. After Yarmouk, the Eastern Roman Empire found it difficult to hold onto most of Syria and had to focus on defending the capital, Constantinople, and Anatolia. This war fundamentally changed the Eastern Roman Empire's territory and strategy.