Budic took advantage of the Bishop's pilgrimage in the Holy Land around 1020 to seize the episcopal possession and destroy the prelate's castle.
This led to the loss of part of the lands held by the Counts of Nantes in the south of Loire, that is to say almost the whole Mauges, in 1025.
The building of Clisson castle was the sign of the Count of Nantes' wish to stop the progression of the County of Anjou.
Around 1030, after a last conflict with Alan III, Budic sided with the Count of Rennes.
On April 5, 1030 he subscribed to a charter by Alan III in favor of Mont Saint-Michel Abbey[1] This crisis led to a decline of the County of Nantes' authority as it was at this time that the first castles were built in the peripheral parts of the pagus of Nantes: Châteaubriant, La Roche-Bernard, Machecoul.