Brienne lies on the banks of the Aube river in a plain called la Plaine de Brienne. The Counts of Brienne dominated the history of the area for a long time. They were one of the most important noble families of medieval France and produced statesmen, diplomats and crusaders. Johann von Brienne (1169/74–1237). He was chosen by the French King Philip II as husband and regent for the heir to the Kingdom of Jerusalem. From 1210 to 1212 he was king of Jerusalem. He then became the father-in-law of the Roman-German Emperor Frederick II, with whom he became enemies and also fought against him as the Pope's general. From 1229 he ruled Constantinople for nine years.
Brienne-le-Château became known as the training site of Napoleon Bonaparte, who studied here for five years (May 1779 to October 1784) as a boarding school student at what was then the Royal Military School. To complete his studies, he left Brienne-le-Château and finished it at the École Militaire in Paris.
On April 3, 1805, he visited Brienne-le-Château again on his trip to Italy for the coronation, now already as Emperor of the French. On January 29, 1814, the Battle of Brienne was fought near Brienne, which ended with a victory for France under Napoleon Bonaparte against the Russians and Prussians under Field Marshal Blücher.
Sources: Wikipedia