In this video, we unravel the fascinating story behind one of the most iconic photographs of the 20th century. May 1910, Windsor Castle: nine crowned heads of Europe stand together, smiling for the camera. Who are these monarchs? What binds them, and what will happen just four short years later? This is no ordinary family portrait; it's a snapshot of world leaders on the precipice of global conflict. We'll show you how emperors and kings, related by blood and dynastic marriages, such as Kaiser Wilhelm II, King George V, King Albert I, King Haakon VII, King Alfonso XIII, and others, found themselves on opposing sides of World War I.