This week’s cover was difficult. It was about the worst humanitarian crisis in the world: the terrible and poorly understood war in Sudan. This is a conflict that erupted out of pure, cynical ambition. Two ruthless military chiefs seized power in a coup, then fell out and started fighting each other. Over the past 500 days or so Sudan has become an inferno. Soldiers and militiamen have killed, burned and raped with impunity. Some 10m people—a fifth of the population—have fled from their homes. Famine is spreading, imperilling millions. As Africa’s third-largest nation collapses, the shockwaves could destabilise swathes of Africa and the Middle East, and send a surge of refugees towards Europe.