took up in Brittany the defence of succession in the male line which he was disputing and fighting against in France.

Philip and his court of peers declared on the 7th of September, 1341, that Brittany belonged to Charles of Blois, who at once did homage for it to the King of France, whilst John of Montfort demanded and obtained the support of the King of England.

War broke out between the two claimants, effectually supported by the two kings, who nevertheless were not supposed to make war upon one another and in their own dominions.

The feudal system sometimes entailed these strange and dangerous complications.
If the two parties had been reduced for leaders to the two claimants only, the war would not, perhaps, have lasted long.
In the first campaign the Count of Montfort was made prisoner at the siege of Nantes, carried off to Paris, and shut up in the tower of the Louvre, whence he did not escape until three years were over.

Charles of Blois, with all his personal valor, was so scrupulously devout that he often added to the embarrassments and at the same time the delays of war.
He never marched without being followed by his almoner, who took with him everywhere bread, and wine, and water, and fire in a pot, for the purpose of saying mass by the way.