The first King of all Brittany, Nominoe, defeats the Frankish king Charles the Bald at the Battle of Ballon near Redon.

The Battle of Ballon took place on 22 November 845 between the forces of Charles the Bald, king of West Francia, and Nomino, Duke of Brittany. Nomino was appropriating border territory and opposing Charles' attempt to impose Frankish authority. Nomino defeated Charles, initiating a period of Breton expansion and consolidation of power.

Brittany (; French: Bretagne [bʁətaɲ] (listen); Breton: Breizh, pronounced [bʁɛjs] or [bʁɛx]; Gallo: Bertaèyn [bəʁtaɛɲ]) is a peninsula, historical country, and cultural area in the west of modern France, covering the western part of what was known as Armorica during the period of Roman occupation. It became an independent kingdom and then a duchy before being united with the Kingdom of France in 1532 as a province governed as a separate nation under the crown.

Brittany has also been referred to as Little Britain (as opposed to Great Britain, with which it shares an etymology). It is bordered by the English Channel to the north, Normandy to the northeast, eastern Pays de la Loire to the southeast, the Bay of Biscay to the south, and the Celtic Sea and the Atlantic Ocean to the west. Its land area is 34,023 km2 (13,136 sq mi).

Brittany is the site of some of the world's oldest standing architecture, home to the Barnenez, the Tumulus Saint-Michel and others, which date to the early 5th millennium BC. Today, the historical province of Brittany is split among five French departments: Finistère in the west, Côtes-d'Armor in the north, Ille-et-Vilaine in the northeast, Morbihan in the south and Loire-Atlantique in the southeast. Loire-Atlantique now belongs to the Pays de la Loire region while the other four departments make up the Brittany region.

At the 2010 census, the population of historic Brittany was estimated to be 4,475,295. In 2017, the largest metropolitan areas were Nantes (934,165 inhabitants), Rennes (733,320 inhabitants), and Brest (321,364 inhabitants). Brittany is the traditional homeland of the Breton people and is one of the six Celtic nations, retaining a distinct cultural identity that reflects its history. A nationalist movement seeks greater autonomy within the French Republic, or independence from it.