"What might spark such a war, and how would it escalate into a global conflict? Here are five potential scenarios: none likely, but all possible. Since 1756, the modern-state system has experienced four global wars; The Seven Years War, The French Revolutionary Wars, World War I, and World War II. The longest global peace came between 1815 and 1914, and it has now been seventy years since the last world war. Every global war needs a spark. A conflict somewhere ignites the interest of more than one great power. World War I had the assassination of Franz Ferdinand; the Seven Years War had desultory fighting between the French and British along the Mississippi River. The combatants do not always appreciate that the sparks can lead to conflagrations."