In the
High Middle Ages, from the 11th century onwards, the Landfrieden movement strove to extend the so-called
Peace and Truce of God (
Gottesfrieden). The first imperial Landfriede was established by Emperor
Henry IV in 1103 for a term of four years and was known as the First Imperial Peace of Mainz (
Erster Mainzer Reichslandfriede). It followed the Mainz Peace and Truce of God (
Mainzer Gottesfrieden), which he had already proclaimed in 1085. In 1152,
Frederick Barbarossa proclaimed the Great Imperial Peace (
Großer Reichslandfrieden), which extended to the whole Empire. This act of constitution brought into effect a time-limited alliance of
ruling princes. It was established in 1186 that a feud had to be announced in
feud letter issued three days in advance. Originating from the law schools in
Bologna and
Pavia, the concepts of
medieval Roman law (
Corpus Juris Civilis) started to dominate the legal profession under Barbarossa's rule. The crucial Imperial Peace of Mainz (''
, also Mainzer Reichslandfrieden
) announced by Frederick II, Holy Roman Emperor at the Imperial Diet of 1235 was more like a legal decree and had less of the character of an alliance. Already in 1231, Frederick had issued the Constitutions of Melfi, a book of codified law and inquisitorial system applying to his Kingdom of Sicily. The Mainz Landfriede'', now applicable indefinitely, was a constitutional act and became one of the
basic laws that applied to the whole Empire. For the first time, this document was bilingually drafted in Latin and
Middle High German. Subsequently, numerous regional and local Landfrieden alliances such as
city leagues () arose during the 13th and 14th centuries. The 1235 Peace of Mainz was renewed at the
diet of Würzburg in 1287 and again in 1290, 1298 and 1354. It was superseded by the
Ewiger Landfriede "Perpetual Public Peace" passed by
Maximilian I, Holy Roman Emperor in 1495, which outlawed any feuds and constituted a permanent Landfriede for the Holy Roman Empire, including the establishment of the
Reichskammergericht "Imperial Chamber Court". == Modern forms ==