At the most famous spot in Sarajevo, where the Appel Quay once met the Latin Bridge that crossed the gentle Miljacka River, there now stand two footprints embedded in the concrete sidewalk. The bridge today is called the Princip Bridge, for these two footprints mark the place where Gavrilo Princip, a gaunt, sallow student of 19, stood and fired the pistol shots that, as one historian put it, took seven million lives.
Princip's 1914 assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian empire, put Europe on the way to World War I, but Sarajevo has been a crossroads of violence for...