Guns and power go together. Like today, most forms of inequality in the global 19th century depended on a weapons gap. The unequal distribution of firearms helped determine power relations both between countries and within countries. Where did all those guns come from? And why did some have so many, and others so few? The Project on Arms Trade History seeks to answer these questions by doing something unprecedented: quantifying the global arms trade between the end of the Napoleonic Wars and the outbreak of World War I. For the past several years, our team has been extracting data from customs reports issued by the globe's major arms-producing and arms-trading nations. We are moving into the final stage of data entry, and need your help to get there.