The above photograph was taken 102 years ago today, on June 28, 1914, and it is one of the most chilling photographs in world history–but only if you know its story. The guy in the feathers is Archduke Franz Ferdinand, heir to the throne of Austria-Hungary, and the woman is Sophie Chotek, his wife; they are emerging from the Town Hall of Sarajevo after an official reception. They had come for a state visit to open a new museum. June 28 also happened to be their wedding anniversary. Earlier in the day a terrorist, part of a Serbian nationalist plot, threw a bomb at the royals’ car, trying to kill them. It missed them but wounded 20 people after it bounced off the back of the car. Ferdinand was furious, and at the reception at the Town Hall berated the mayor of Sarajevo for the hostile welcome. After the reception Ferdinand and his wife decided to cancel the next part of their schedule and visit the wounded from the bombing at the hospital. This photo was taken as they were walking to their car. Ten minutes after this picture was taken they were both dead.

Another terrorist, Gavrilo Princip, struck just as the car was driving away. He fired two shots at nearly point-blank range. He was immediately apprehended, but the fuse had been lit that began to burn down to the outbreak of what was then the world’s worst conflict. World War I, a cataclysm primed to destroy a fragile European order of seething nationalist hatreds and entangling alliances, snuffed out 10 to 20 million lives, laid waste to entire nations and completely upended the world order. It wasn’t really about Franz Ferdinand, but his death was the trigger that set off the whole horror. That’s why this picture is quite chilling to look at.

It is uncertain exactly who took this photo, but it’s one of the most fateful and important photographic images of the 20th century. I’d put it up there with Dorothea Lange’s “Migrant Mother” or the famous “tank man” photo from Tiananmen Square so far as historical import is concerned. The scary thing about history is that you never know when it’s about to change dramatically. These days a casual snapshot taken on a cell phone could, in certain circumstances, be the very last photo ever taken during an entire epoch of history. Such a picture might someday wind up like this one.

This image is in the public domain.