State · 939 – 1547

Duchy of Brittany

A state of 939 – 1547 — 608 years in Europe. It followed Kingdom of Brittany. The atlas records 6 things within it — wars and battles 1 · people 5. Its line of rulers holds 4 people.

For the full story, the article on Wikipedia (CC BY-SA 4.0); this page holds what the record says of the state.

Stood: 608 years; 939 – 1547
Rulers: 4; the duke of Brittany
Most ground: 37,300 km²; in 1152
Within it: 6; recorded rows
Symbols: 3; on record, with years

Map: Duchy of Brittany in 1152, its borders in gold among its neighbours — Duchy of Brittany in 1152, when it held the most ground the borders dataset draws for it: 37,300 km². Its neighbours wear their tints, as on the atlas's own map. Borders from Cliopatria (CC BY 4.0), coast and rivers from Natural Earth, cities from Reba, Reitsma & Seto 2016 (CC BY 4.0), each city under the name it bore that year.

Where it sits in time

Five thousand years, 3000 BCE to 2026; the state in gold, what it replaced or followed and what replaced or followed it in grey.

Before and after

The states the record files it as replacing or following, and those that replaced or followed it - Wikidata's own statements, each read from this state's side.

Before it

Kingdom of Brittany · follows · 851 – 939

Rulers

The line of duke of Brittany - the office this state names as its head of state.

killed, executed or dead in battledeposed, abdicated, exiled or removeddied in officea second row: a reign that began before the last had ended — rival claimants, or a shared throne

Ruler	Reign	Length	How it ended · source	To the ruler before
Conan IV of Brittany	1156 – 1166	10 years	abdicatedWikidata's end cause on the term
Constance of Brittany	1166 – 1201	35 years	died in office of natural causesWikidata's manner of death	child
Geoffrey II of Brittany	1181 – 1186	5 years	died by accidentWikidata's manner of death	spouse
Arthur I of Brittany	1196 – 1203	7 years	killedWikidata's manner of death	child

4 rulers, 4 with terms dated as terms, covering 1156 – 1203. Only 47 years of the line are dated - too short for a median. 1 of 3 handovers irregular - a killing, a deposition, a rival claimant, a rising or a coup beside it. A blank in the last column means no kin on record, which is coverage, never “unrelated”.

Ground held, by year

km² inside its borders as the borders dataset draws them, measured on an equal-area grid; a step series, held between the years the dataset maps.

31,900 km² in 964, 37,300 km² in 1489; at its largest 37,300 km² in 1164. Cliopatria, CC BY 4.0.

Flags and arms, in order

Each symbol with the years its own statement gives; the timeline flies the one of the year on screen.

coat of arms, undatedArmoiries Bretagne - Arms of Brittany · Public domain
flag, undatedDrapeau de la province de Bretagne (1532) · CC BY-SA 4.0 · This image has been made by GwenofGwened and released under the licenses stated below. Yo…
coat of arms, undatedBlason Pierre Ier de Bretagne · CC BY 3.0

What happened within it, by century

Every row the atlas hosts under this state, by the century it began in: wars and battles in red, risings, regime changes and massacres beside them, everything else in grey. A tall bar is a century the record is full for, which is partly a fact about Wikipedia.

1100 – 11994 rows

Geoffrey II of Brittany · ruler · 1158 – 1186
Arthur I of Brittany · ruler · 1187 – 1203
Constance of Brittany · ruler · 1161 – 1201
Conan IV of Brittany · ruler · 1138 – 1171

1300 – 13992 rows · 1 wars and battles

War of the Breton Succession · war · 1341 – 1365
John IV of Brittany · person · 1339 – 1399

Among all states

Each measure against the states that carry it, never against all of them: a bar is the share of those states below this one.

How long it stood608 years
stood longer than 90% of 3,187 states with a recorded end or still standing.
The most ground it held37,300 km²
held more ground at its peak than 30% of 1,465 states with a border in Cliopatria.
Wars recorded per century0.2
had more wars on record per century than 89% of 3,187 states, counting the wars the atlas hosts under each.
Rulers on record4
has more rulers on record than 58% of 1,968 states with a line of rulers.

What led to it, and what came of it

The investigation's own picture: 1 cause the record names and 0 results, the strongest six of each at their own years, joined to the state by the kind of claim - a recorded statement solid, the article's sentence dashed, a theory dash-dot.

linked

Open the investigation: every row with its evidence, the conditions at the time, the theories condition by condition, and the succession analysed.

Open in the atlas

On the timeline, 878 – 1608, with everything that stood beside it.
On the map in 1152, live: scrub the year and watch its borders move.
Investigate it: what led to it, what came of it, and its succession analysed.

Wikidata Q71747 (CC0) · borders Cliopatria, CC BY 4.0 · coast and rivers Natural Earth · symbols from Wikimedia Commons, each credited above · data built 2026-10-06 · Pastlas v2.9.1, by Oleh Voronko. The published atlas and its data are for non-commercial use.