Khalid ibn al-Walid Khalid ibn al-Walid ibn al-Mughira al-Makhzumi ( Arabic : خالد بن الوليد بن المغيرة المخزومي , romanized : Khālid ibn al-Walīd ibn al-Mughīra al-Makhzūmī ; died 642) was a 7th-century Arab military commander. He initially headed campaigns against Muhammad on behalf of the Quraysh . He later became a Muslim and spent the remainder of his career in service to Muhammad and the first two Rashidun caliphs : Abu Bakr and Umar . Khalid played the leading command roles in the Ridda Wars against rebel tribes in Arabia in 632–633, the initial campaigns in Sasanian Iraq in 633–634, and the conquest of Byzantine Syria in 634–638. [ 2 ] As a horseman of the Quraysh's aristocratic Banu Makhzum clan, which ardently opposed Muhammad, Khalid played an instrumental role in defeating Muhammad and his followers during the...