devastating as much of Archambaud's land as possible. This they excelled at, conducting a chevauchéea large-scale mounted raidinto Périgord, burning property and killing the inhabitants. Pembroke's force then captured Bourdeilles castle after an eleven-week siege when a mistimed sortie allowed the English entry. Knighted soon after by the Earl of Cambridge, Pembroke continued to campaign in both Anjou and Poitou. This involved much raiding, some of it alongside the Black Prince. By June Pembroke was raising a large army to relieve French pressure on the north of Poitou. He and Cambridge were joined by Sir John Chandos around this time. They arrived in the Vendée at the end of June 1369, and captured Roche-sur-Yon as a result of the French captain betraying the town. This was a strategically important French-held enclave inside English France, and it belonged to the Duke of Anjou. Following the taking of Roche-sur-Yon Pembroke led a successful campaign into the Loire Valley. Although he failed in an attempt to capture Saumur, he took and held both of the main bridges across the river Loire between Saumur and Nantes. They were already strongly fortified and Pembroke strengthened these defences and garrisoned them. This campaign greatly diminished the ability of the French to attack through the western march of Poitou. Disagreements and tensions arose among the English generals, particularly between Pembroke and Chandos, based on their vastly different social status. As the modern historian Jonathan Sumption puts it, Pembroke "may have had the grander name but his inexperience showed". Although Chandos was appointed seneschal of Anjou he was only a banneret and so Pembroke, with aristocratic arrogance, refused to serve under him. It is possible Pembroke was acting on the advice of his council, but the result was that the two English armies were kept separate from each other. In October (or possibly December) Pembroke invaded Anjou with just his own force of 300 men-at-arms on a fire-raising raid to Puirenon. During this Pembroke was ambushed by about 600 men under either Louis de Sancerre or Jean de Bueil. Taken by surprise, Pembroke's men were still trying to form up when they were charged by French cavalry. About 100 of the English were killed or taken prisoner, and the French captured supplies, horses and materiel. Unable to fight the attacking force off, Pembroke escaped to a house at the edge of a village and sent to Chandos for