One of the outstanding features of the Iran-Iraq War (1980-88), particularly in the Iranian perspective, was that the Islamic Republic was widely viewed as the more dangerous and aggressive of the belligerents despite the fact that Iraq initiated the conflict by invading Iran in September 1980. Both during and since the war, the policies of the Islamic Republic and the geopolitics of the Middle East have combined to produce the conception that Iran represents the primary threat to the security and stability of the region. The wartime policy that contributed most significantly to that conclusion was Iran’s 1982 invasion of Iraq. Several decades later, Iran’s decision to continue the war following the liberation of most of its territory remains a point of contention and misunderstanding. While for many analysts the decision exemplifies the aggression, irrationality, and ideological zeal that make the Islamic Republic so dangerous, serious attempts to uncover Iran’s motives have been lacking. In most cases the Iranian invasion has been interpreted as resulting from a combination of revolutionary overreach, the dogmatism of the regime’s hardline factions, and the oversized influence of Iran’s Islamic Revolutionary Guards Corps (IRGC). The evidence used to support the conclusion, meanwhile, has been far from robust, with most scholars relying on the memoirs of Iranian leader Akbar Hashemi Rafsanjani and a slew of non-Iranian sources. This paper complicates the prevailing wisdom regarding the Iranian invasion. It is based on research conducted for a book project that examines how the IRGC has documented the Iran-Iraq War. It focuses particularly on the IRGC’s Center for Holy Defense Documentation and Research (the Center), which is one of the most active Iranian research and publication institutions that deals with the Iran-Iraq War. The Center’s work, however, has largely been overlooked by scholars, and its significance has therefore remained understudied and underappreciated. Yet, as my research demonstrates, the work of the Center is of immense value for understanding Iran’s opaque decision-making process during the war. Indeed, for the IRGC the Iranian invasion was an act not of aggression but of defense. The decision to pursue the war’s original aggressors into their own territory, the IRGC accounts assert, was made carefully and rationally and only after the invasion was deemed necessary to restoring Iran’s national security. Dreams of marching straight through Iraq and onward to Jerusalem—though useful rhetorically to rally the troops—played no role in the decision-making process.