Battle of Yarmouk

The Battle of Yarmouk (636 AD) is one of the most significant battles that took place during the caliphate of Abu Bakr, as the Islamic conquests spread into Syria and Palestine. At the end of the 12th year of Hijra, Abu Bakr sent four separate armies towards Syria: forces under the command of Abu Ubaidah ibn al-Jarrah, Amr ibn al-As, Yazid ibn Abi Sufyan, and Shurahbil ibn Hasana. To unite the strength of these armies and make a full-scale offensive, Khalid ibn al-Walid was transferred from Iraq to Syria. The Byzantine army gathered at Yarmouk consisted of one hundred thousand or more soldiers. The Muslims faced this massive army with a much smaller force. With Khalid ibn al-Walid's superior tactical intelligence and the high morale of the Muslims, the Byzantine army was dealt a significant defeat. This victory accelerated the Muslim control over Palestine and Syria. [Source: "Battle of Yarmouk", TDV Islamic Encyclopedia, https://islamansiklopedisi.org.tr/ecnadeyn-savasi]