The cobbled town of Bourges lies in France’s “empty diagonal”: the central swathe of farmland that city folk zoom past on their way to somewhere else. In 1860 Napoleon lll decided to build a cannon foundry and arsenal there, a place safely remote from France’s fragile eastern borders. Home to just 64,000 people, Bourges was until recently bleeding jobs as its modern weapons-makers lost orders. “There was a long period of depression,” recalls Serge Richard, head of the local chamber of commerce.