A six-day battle in a sandstorm ended 600 years of Roman rule in Syria

In August 636, near the Yarmouk River, a Rashidun Arab army under Khalid ibn al-Walid ground down a much larger Byzantine force over six days of attritional fighting. A sandstorm blew into the Byzantines' faces at the decisive moment, and their army broke and was destroyed. The defeat permanently ended Byzantine control of Syria and opened the region to thirteen centuries of Muslim rule.

— Wikipedia contributors, Battle of the Yarmuk — Historical overview of the 636 CE battle