On November 9, 2016, newspaper headlines across the country—and around the world—heralded the outcome that almost no one expected: Donald J. Trump won. "Hillary Rodham Clinton's Ground Game Will Sink Trump" said a headline in Politico; "Clinton Holds Huge Ground Game Advantage over Team Trump," reported The Hill. Field is one of the many areas of political campaign work that seems aptly compared to war preparations: there are vehicles, routes, personnel, fuel, food, lines of communication, and even reconnaissance. The Obama campaign, on the other hand, had the good fortune of building on a field operation that it had started before the 2008 primaries—which in some states had been operating nearly continuously for almost five years. Field organizers are deployed to battleground states, where they recruit volunteers and allied organizations to talk to as many voters as possible and get them to the polls on Election Day or during early voting.