Investiture Controversy – Wikipedia

The Investiture Controversy or Investiture Contest (German: Investiturstreit, pronounced [ɪnvɛstiˈtuːɐ̯ˌʃtʁaɪt] ⓘ) was a conflict between the Church and the state in medieval Europe over the ability to choose and install bishops (investiture)[1] and abbots of monasteries and the pope himself. A series of popes in the 11th and 12th centuries undercut the power of the Holy Roman Emperor and other European monarchies, and the controversy led to nearly 50 years of conflict.
— Read on en.m.wikipedia.org/wiki/Investiture_Controversy