In the early 11th century, the Peace of God movement spread across Europe. It attempted to stop feuding by making nobles swear oaths to let the arms rest on certain days. These oaths were taken on holy relics and a breach would bring spiritual punishment incl. excommunication.
The Peace of God movement was an act of desperation in parts of Europe where the authorities were unable to maintain order. It originated in France where central power under King Henri I (1031-1060) had shrunk to just the Ile de France (see recent post).
The (“German”) Emperor Henry III (1039-1056) borrowed some elements of the Peace of God movement. In 1043 he held a Synod where he assembled the nobles of Swabia. He first forgave every trespass committed against him. And then through prayers and exhortations he achieved a mutual reconciliation amongst all the Swabians present. They in turn forgave each other any trespass committed against them.
These peace happenings were repeated all across the country. The chronicler Hermann of Reichenau described the outcome as “a peace unheard of for many centuries that the king confirmed in an edict”.
The last sentence matters most: “confirmed by edict”. In other words, irrespective of the religious pomp, Henry III did order peace or more precisely banned feuding by secular law. There were only two rulers in Western Europe at this point who had enough centralised power to do that, the Duke of Normandy and the Emperor.
When people quote Voltaire’s quip that the Holy Roman Empire was neither Holy nor Roman nor an Empire in relation to the 11th century, they could not be further from the truth. Leaving aside that the term Holy Roman Empire only coming into usage 200 years later, by 1044 the Empire was indeed sacred, led by a sacred ruler, it had inherited the ambitions of the Roman empire, and it was very much an empire, the most powerful and coherent political entity in Western Europe.
More on Henry III in Episode 26f of the History of the Germans