Battle of Ullais

Battle context

The Battle of Ullais, fought in June 633 in Iraq, was one of the early engagements of the Rashidun Caliphate's push into Sasanian Persia. The scale of recorded casualties — 70,000 on the Sasanian side against 2,000 for the Rashidun forces commanded by Khalid ibn al-Walid and Al-Muthanna ibn Haritha — indicates a decisive Rashidun victory, though the battle's outcome is not formally recorded in the structured record. The engagement is sometimes called the Battle of Blood River, a name that reflects the reported magnitude of Sasanian and Arab Christian losses. As an early action in the Muslim conquest of Persia, Ullais contributed to the erosion of Sasanian military capacity in the Iraqi theater, forming part of the initial Rashidun offensive that would ultimately bring the Sasanian Empire to collapse over the following two decades.