The first ruler of this kingdom joined Ongendus's son Sigfred in attacking 
The first ruler of this kingdom joined Ongendus's son Sigfred in attacking the lands of Charles the Fat, joining an 885 siege of a city defended by Count Odo and later agreed to the Treaty of Saint-Clair-Sur-Epte, swearing fealty to Charles the Simple after losing at Chartres. Otto IV's disastrous loss at Bouvines helped trigger the Magna Carta when John Lackland lost his barons' overseas holdings in this kingdom, the home of Rollo and Robert Guiscard. For 10 points, identify this kingdom from which William the Conqueror invaded England, found East of Brittany on the Northern coast of France.
The first ruler of this kingdom joined Ongendus's son Sigfred in attacking the lands of Charles the Fat, joining an 885 siege of a city defended by Count Odo and later agreed to the Treaty of Saint-Clair-Sur-Epte, swearing fealty to Charles the Simple after losing at Chartres.
{Normandy}