...It’s probably no coincidence that the man who once said “an army travels on its stomach” was Europe’s first head-of-state tater-booster. So effective was the crop that Frederick the Great of Prussia ordered his government to distribute free seed potatoes and planting instructions throughout his kingdom. That proved smart: Prussian peasants survived French, Austrian, and Russian invasions in unprecedented numbers.
Those invaders soon caught on, encouraging their own plebeians to grow the crop. To this end, Marie Antoinette once sported a potato-flower headdress at a court ball to extol the tuber’s virtues, as McNeill recounts.
The crop certainly did make it easier to staff and feed vast armies. For instance, in the late 1770s, potatoes fed both sides fighting the War of Bavarian Succession, which ended when Bohemia ran out of potatoes.
The Potato War, as it’s sometimes known, doesn’t reflect the potato’s broader promotion of peace, however. The potato’s spread caused a sharp fall in the incidence of conflict, as three economists—the University of Colorado’s Murat Iyigun, Nathan Nunn of Harvard, and Nancy Qian at Northwestern’s Kellogg School of Management—document in a new working paper (registration required) published by the National Bureau of Economic Research.
That may have been because people mainly fought over land, and land’s prime value came from agriculture. Increased productivity would have effectively driven down land values, lowering incentives to shed blood fighting over it, they argue. If higher productivity pushed up real wages for peasant farmers, as you’d expect, the opportunity cost of rioting would climb—as it would, too, for rulers who taxed labor for revenue.
Wars still broke out, of course. But the potato’s spread dramatically limited the destructive consequences of conflict...