Nonmaterial variables are important in war, but can be difficult to study quantitatively given their absence from standard datasets. We present a method for overcoming this challenge by using optical character recognition (OCR) software and a process of crowdsourced data conversion to code narrative archival records at scale, producing large-n data on nonmaterial variables such as force employment, combat motivation, leadership, culture, initiative, organizational structure, or military doctrine. We illustrate this method by coding a new dataset on the determinants of success and failure in submarine warfare, and demonstrate its utility with a preliminary analysis of the resulting data. Tentative findings suggest that nonmaterial variables are likely to matter for naval combat in ways that would render analyses based on materiel alone suspect, but that not all nonmaterial traits matter equally. Many believe that initiative and leadership, in particular, are important determinants of success in combat – and indeed they may well be. But our initial analysis suggests that for submarine combat in World War II they may have been less important than the intellectual and personal qualities that produced strong performance at the Naval Academy.