First Council of Lyon

The condemnation of the emperor was a foregone conclusion. The objections of the ambassador, that the accused had not been regularly cited, that the pope was plaintiff and judge in one, and that therefore the whole process was anomalous, achieved as little success as his appeal to the future pontiff and to a truly ecumenical council.^[6]

At the second session on 5 July, the

• It obliged the Cistercians to pay tithes
• It approved the Rule of the Grandmontines
• It decided the institution of the Octave of the Nativity of the Blessed Virgin
• It prescribed that
  cardinals were to wear a red hat^[7]
• It prepared thirty-eight constitutions which were later inserted by
  Boniface VIII in his Decretals, the most important of which decreed a levy of a twentieth on every benefice for three years for the relief of the Holy Land.^[8]

• Addington, Larry H. (1994). The Patterns of War Through the Eighteenth Century. Indiana University Press.
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• Ambler, S. T. (2017). Bishops in the Political Community of England, 1213–1272. Oxford University Press.
  ISBN 978-0198754022
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• Bellitto, Christopher M. (2002). The General Councils:A History of the Twenty-One Church Councils from Nicaea to Vatican II. Paulist Press.
  ISBN 978-0809140190
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• Biller, Peter (2000). The Measure of Multitude: Population in Medieval Thought. Oxford University Press.
  ISBN 978-0198206323
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• Dondorp, Hary; Schrage, Eltjo J.H. (2010). "The Sources of Medieval Learned Law". In Cairns, John W.; du Plessis, Paul J. (eds.). The Creation of the Ius Commune: From Casus to Regula. Vol. 7. Edinburgh University Press.
  ISBN 978-0748638970
  .
• Hefele, Karl Joseph von (1913). H. Leclercq (tr.). Histoire des conciles d'après les documents originaux. (in French and Latin). Vol V, part 2. Paris: Letouzey, 1913.
• Maiorov, Alexander V. (2019). "The Rus Archbishop Peter at the First Council of Lyon". The Journal of Ecclesiastical History. 71 (1): 1–20.
  S2CID 211652664
  ..
• Martínez, H. Salvador (2010). Alfonso X, the Learned. Translated by Cisneros, Odile. Brill.
  ISBN 978-9004181472
  .
•  This article incorporates text from a publication now in the public domain: Mirbt, Carl Theodor (1911). "Lyons, Councils of". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 17 (11th ed.). Cambridge University Press. pp. 176–177.
• Richardson, Carole M. (2019). "The Cardinal's Wardrobe". In Hollingsworth, Mary; Pattenden, Miles; Witte, Arnold (eds.). A Companion to the Early Modern Cardinal. Brill. pp. 535–556.
  ISBN 978-9004310964
  .
• Wolter, Hans; Holstein, Henri (1966). Histoire des conciles œcuméniques: Lyon I et Lyon II. (in French). Pars: Éditions de l'Orante, 1966.

• First Council of Lyon