Battle of Carrhae, Surena defeats Rome, Khordad 19. This observance marks the historic battle between the Parthian army led by Surena and the Roman forces commanded by Crassus, which took place in the year 506 Shahanshahi (corresponding to 53 BCE) near the city of Carrhae. The battle stands as one of the most significant military encounters between Iran and Rome in antiquity and ended with a decisive defeat for the Roman army. In this engagement, Surena, a prominent Parthian general, utilized light cavalry and skilled archers to encircle and overwhelm the Roman forces, which numbered around 40,000. Crassus, the Roman commander, along with his son and many senior officers, was killed, and thousands of Roman soldiers were either killed or captured. It is estimated that about 20,000 Roman soldiers died in the battle, with another 10,000 taken prisoner. Surena’s victory at Carrhae marked a turning point in the history of Iran-Rome relations and solidified the military power of the Parthians in the region. This event is commemorated in the Shahanshahi calendar as a reminder of one of ancient Iran’s greatest military victories. The day is typically observed by recalling Surena’s role and the significance of the Battle of Carrhae in Iranian history. The inclusion of this day in the Shahanshahi calendar was made by decision of Iranian cultural and historical institutions in the modern era, in order to highlight the importance of this historical event and to familiarize future generations with the military and political achievements of ancient Iran.