Complex sentence: The most significant jurisdiction change occurred after the Concordat of 1801, when the diocese annexed the department of Haute-Marneuntil 1821; after which the Papal Bull re-established the Diocese of Langres.
Split into simpler sentences: The most significant jurisdiction change occurred after the Concordat of 1801, when the diocese annexed the department of Haute-Marne. In 1821, a Papal Bull re-established the Diocese of Langres.