On 22 September 1980, Iraqi forces started their invasion of Iran, heralding the longest conventional war in the twentieth century. A year earlier, both Saddam Hussein in Iraq and Ruhallah Khomeini in Iran consolidated their power. Saddam aspired regional dominance due to the waning power of neighbor Arab countries. Employing realism, with a more emphasis on Iraq, it assumes rational actor model and that Iraq is a united entity. Such a theory does not touch upon intra-conflict regarding other entities in Iraq. Shia communities and army generals played a crucial part outside the sovereignty of the regime, whether colluding or attempting to stage a coup. Iran-Iraq literature argued that Saddam went to war, fearing the impact of his neighbor Islamic Revolution on his country. According to Iraqi officials, the reason was otherwise. Opportunity prevailed over fear. While Realism explained conflicting interests, constructivism would explain more. Incorporating ideational aspects along material ones, the extent to which constructivism deals with causes of war is substantially convincing, ontologically speaking. Discourses prior to the war and the ongoing process in which interaction transformed from rivalry into enmity illustrate the theoretical capacity of constructivism.