The Battle of Fahl (Arabic: يوم فحل, Yawm Faḥl), also known as the Battle of the Marshes (Yawm al-Radagha) and the Battle of Beisan (Yawm Baysān), was a major battle in the Muslim conquest of Byzantine Syria fought by the Arab troops of the Rashidun Caliphate and Byzantine forces at or near Pella (Fahl) and nearby Scythopolis (Beisan), both in the Jordan Valley, in December 634 or January 635.