In 1618 a comet crossed the sky and, within months, Europe slid into the Thirty Years' War, a conflict that started as a Protestant-Catholic dispute and pulled in Sweden, France, and Spain before it burned out three decades later. This film builds its account around the diary of Peter Hagendorf, a German mercenary who recorded his marches, battles, and losses from 1625 to 1649, one of the only detailed firsthand accounts of ordinary soldiering to survive the war. Historians walk through Hagendorf's entries alongside period maps, paintings, and battlefield sites to reconstruct what a mercenary's daily life actually looked like: the pay disputes, the plunder, the disease, the burial of his own children along the road. The war's scale is kept in view throughout, including the collapse of Germany's population and the redrawing of European power that followed. Rather than a broad campaign history, this is the war seen through one soldier's boots, which makes the violence and hardship of the period harder to look away from.