This chapter will appear in an upcoming book devoted to Big Data and International Humanitarian Law published by the Lieber Institute at West Point. As this volume reveals, big data has the potential to dramatically alter how war is waged, how the international community responds to conflicts, and how artificial intelligence-enabled capabilities can help parties enhance (or evade) compliance with the law of armed conflict (LOAC). Big data and big data analytics are already revolutionizing the practice of law—including processes of litigation discovery, sources of proof, and sentencing—in times of peace. This chapter surveys the opportunities and challenges presented by big data when it comes to the enforcement of LOAC and the prosecution of war crimes. The war in Syria—the first conflict in the modern social media era and the most documented crime base in human history—is illustrative. In prior conflicts, amassing enough evidence to stage a viable war crimes trial was often a principal challenge; today, the problem may be the reverse: there is too much documentation, which can overwhelm legal actors seeking to impose individual criminal responsibility. This article explores this conundrum in several parts. It first discusses the sources and potential utility of the mixed masses of evidence emerging from today’s armed conflicts. It then sketches out several potential methods for identifying, processing, and analyzing big data in war crimes prosecutions, including object recognition and event detection, facial recognition, statistical analysis of targeting patterns, social networking analysis, and 3-D modeling. Notwithstanding these promising opportunities to enhance the criminal enforcement of LOAC, a number of challenges remain to fully exploiting big data in the service of accountability. Even with emerging big data analytics and growing computational power, modern armed conflicts—being complex, cross-domain, dynamic, and unpredictable—simply do not lend themselves to easy analysis.