Barons and castellans · Other imperial lands · as at first light, 1 January 1200

Cossonay-Prangins

One of the old baronial houses of the Vaud, holding Cossonay on the plateau and, on the lake shore, Prangins with the old Roman town of Nyon.

Nyon belongs to the archbishop of Besançon, who gave it in fief to the lords of Prangins in the 1130s; Savoy gets the overlordship only in 1272 and the town by force in 1293. In 1200 the house answers to no prince on the ground, between the bishop of Lausanne, the Zähringen rector and the counts of Geneva.

Who he is

Name
Jean of Cossonay (died about 1230)
Title
Lord (sire) of Cossonay and Prangins
Since
not pinned
Born
not pinned
Family
Grandson of Humbert (attested 1096-1147), lord of Prangins and Nyon, and great-grandson of Ulrich, the first of the house (1096). Marriage ties with the Gruyère, Estavayer, Grandson and Montbéliard houses. After Jean's death the house splits and the name Cossonay passes to the branch of Cossonay, L'Isle, Bercher and Surpierre.
Confidence
medium

HLS article on the house; it names no other member alive about 1200, so Jean as lord that winter is a reasonable reading, not a dated fact.

Overlord

For Nyon, the archbishop of Besançon (Amadeus of Tramelay), whose church has held it since about 1032 and enfeoffed it to the lord of Prangins in the 1130s; for Cossonay, the bishop of Lausanne's county of Vaud in name.

What it holds

  • Cossonay: castle and lordship on the plateau north-west of Lausanne
  • Prangins: castle and lordship on the lake shore
  • Nyon: the town and lordship, a fief of the archbishop of Besançon since the 1130s; its own villages later counted Arzier-Le Muids, Bassins, Eysins, Saint-Cergue, Signy-Avenex and Trélex

How it was acquired

Prangins and Nyon held since the early 12th century (Humbert, 1096-1147); Nyon in fief from Besançon since the 1130s.

Allies and rivals

Kin by marriage of the Gruyère, Estavayer, Grandson and Montbéliard houses. The counts of Geneva and the lords of Gex are the neighbours across the lake road; Savoy becomes the enemy in the mid-13th century.

How things stand that morning

Holds Cossonay, Prangins and Nyon. No side in the throne war recorded.

Wealth

The lake road from Geneva to Lausanne and the landing at Nyon; vineyards and grain of La Côte; the plateau lands round Cossonay.

Military

Castles at Cossonay, Prangins and Nyon; vassal knights of the Vaud. No war recorded in 1198-1199.

Threats

  • The Zähringen rector's pressure on the Vaud nobility
  • Later, Savoy, which takes Nyon in 1293

Places of note

  • Nyon: Town and lordship, fief of Besançon
  • Prangins castle: Castle of the house

Where the sources disagree

  • The OMNIA board enters Nyon under the bishop of Lausanne because 'its lordship in 1200 cannot be fixed to one family'. The HLS puts Nyon under the archbishop of Besançon from about 1032, enfeoffed to the lords of Prangins in the 1130s; we follow the HLS.

Evidence: The tenure of Nyon and Prangins is dated by the HLS; the lord's name for 1 January 1200 is inferred from the genealogy.

On the map: Village lists come from the later bailiwick of Nyon; ground at Cossonay may already be drawn for other realms.

Primary sources for Empire

Chronicles, registers, sagas and inscriptions written in or near 1200 that cover this entry. Each has its own page with editions, translations and where to read it.

8 more in the sources library for The Rhineland, the Low Countries and the Swiss Lands.

Sources and studies

  1. HLS: Nyon (seigneurie, district)
  2. HLS: Cossonay, de

Last revised 4 November 2026. Published 4 November 2026. Suggest a correction on the OMNIA Discord.