Much of the food Americans buy at the grocery store has a secret military history. According to food writer Anastacia Marx de Salcedo, author of the new book Combat-Ready Kitchen: How the U.S. Military Shapes the Way You Eat, many packaged, processed foods Americans see on grocery store shelves and in refrigerator cases today were originally intended to serve as combat rations for soldiers out in the battlefield. For example, today’s energy bars are the result of a decades-long quest to find an emergency ration that was small, light and nutritionally rich. The very first energy bars were known as the “D ration,” an emergency bar made of chocolate, sugar, cocoa butter, skim milk powder and oat flour. The D ration didn’t taste very good, but