The breaking of Ghouta was a pivotal event in the Syrian war. Its fall removed any enduring threat to the Syrian capital, freed up Syrian government military resources for other fronts, demoralized Syrians opposed to President Bashar al-Assad, both armed and unarmed, and demonstrated that his forces were confident enough with their military situation to attack a heavily fortified opposition stronghold, ostensibly protected by an internationally recognized de-escalation agreement. Capturing Ghouta rewarded the government and its allies for years of visible mass atrocities and continued to weaken the international rules-based order. This report provides an evidence base for a concerted effort to hold the perpetrators of mass atrocities accountable, helping to demonstrate that regimes may not act with impunity against their own people.