Introduction The First Fitna, or the First Islamic Civil War, is considered to be the first civil war in the Islamic Caliphate. The war began in 656 CE and ended in 661 CE which can be evaluated as rather a long period. There were many reasons for the beginning of this war; however, the major reason was the death of the Caliph Uthman. His assassination by the Egyptian rebels was seen as an act of utter disrespect to Mohamed as Uthman was one of his closest companions. For this reason, Uthman‘s death was to be revenged. However, the next ruler, Ali, failed to punish the guilty ones properly and showed his weakness. This caused the anger of Uthman’s supporters and became a ground for a Civil War. The First Fitna had many important consequences for the development of the relationships between the Muslims belonging to Sunni and Shi’i. Unfortunately, these relationships were much worsened during the period of the First Islamic Civil war. Evaluating the situation, it appears that the First Islamic Civil war led to the split in the Muslim religion caused by the effects of the Arbitration Agreement developed after the battle of Siffin. Main body The events of the beginning of the war First of all, speaking about the First Fitna, the events leading to its begging are to be addressed. Among a variety of reasons for the beginning of the First Islamic Civil War, the major reason is seen in the death of the great Caliph Uthman. Uthman was captured by the rebels, and assassinated in 656 CE. According to Hickman (2011, par. 1), “following the murder of Uthman ibn Affan, the caliphate of the Muslim Empire passed to the cousin and son-in-law of the Prophet Muhammad, Ali ibn Abi Talib”. However, the new ruler, Ali, had several opponents, and the most influential of them was Muawiyah I, the governor of Syria (Bonner, 2006). Muawiyah I was Uthman’s devotee. He saw a weak person in Ali and feared that he would not be able to revenge Uthman’s death (Hawting, 2000). Ali understood that the conflict with Muawiyah I was an inevitable danger, and wanted to maintain peaceful relationships with him by all means. For this reason, he sent his messengers to Muawiyah I with the proposition of peace. Muawiyah I received these prepositions on condition that Ali would punish all the guilty ones in Uthman’s death. However, the conditions were not submitted by Ali which resulted at the beginning of the civil war between the two governors. Battles in As a result, the two battles in Bassorah and Siffin led to the later arbitration between Muawiyah I and Ali took place. The battle of Bassorah occurred in 656 CE between the army of Ali and the army of Aisha, a widow of Muhammad who wanted revenge for Uthman’s death. Aisha as Muhammad’s widow and the mother of faith was desperate about Uthman’s death because he was one of the closest associates of her husband. The battle of Bassorah became a date of the beginning of the First Civil War in the Islamic Caliphate (Ruthven 2000). This battle is marked as a notorious battle in Islamic history as it became the first battle when Muslims fought Muslims. In total, the combat lasted for 110 days and took away the lives of more than 10 000 people from both armies. During the battle of Bassorah, Aisha’s army was defeated by Ali’s warriors. However, he showed mercy to the woman and offered her the help of her brother, one of Al