Lambert ruled the county in opposition to Amaury, the puppet count installed by Charles the Bald, King of West Francia.
Disappointed in his ambitions, Lambert II broke with Charles the Bald and turned to Nominoe, Duke of Brittany, who was then in almost open revolt against the Franks.
Lambert gathered soldiers on the borders of the Anjou, intending to advance on the river Vilaine to join his forces with Nominoe.
Renaud invaded Breton territory at the junction of the Diocese of Alet and County of Nantes, on the Roman road of Angers-Carhaix.
An army of Bretons led by Nominoe's son Prince Erispoe was crossing the Vilaine at Messac when Renaud attacked.
[4] However in 850 Lambert and his brother Warnar renewed their alliance with Nominoe and both raided Maine "with unspeakable fury" according to the Chronicon Fontanellense.