historian Clifford Rogers suggests that these 2,300 men were reinforced by up to 1,700 men from Navarrese-held fortifications over the following month. Chevauchée Lancaster's main objective was to relieve the besieged Navarrese strongholds of Pont-Audemer, Breteuil and Tillières-sur-Avre. Lancaster's small army set off into French-controlled Normandy on 24 June. Their journey took the form of a . All participants were mounted and moved relatively rapidly for armies of the period. Villages were looted and razed, as were towns and fortifications weak enough to be easily captured; stronger places were ignored. Parties spread out from the main line of travel so that a broad swathe of France was pillaged and devastated. Grosmont was prepared for a set-piece battle if necessary, but was not actively seeking one. His small army arrived at Pont-Audemer after covering more than in four days. The town was close to falling, as the French had nearly succeeded in driving mines under its walls. They fled on hearing of Grosmont's approach, abandoning their baggage and siege equipment. The English spent two days provisioning the town and filling in the French excavations. Detaching 100 men to reinforce the garrison, Grosmont marched south on 2 July. On the 4th he reached Conches-en-Ouche, stormed it and razed it. The next day Breteuil was reached, its besiegers having retired in good order, and was resupplied sufficiently to stand a siege for a year. Meanwhile, John had left Chartres with a large force, initially establishing himself at Mantes. When Grosmont marched east, John believed he was striking for Rouen, and moved his army there. John also took steps to block the fords across the Seine, in the belief Grosmont may have been heading for Calais. Once it became clear Grosmont was moving south from Pont-Audemer, John followed. Just to the south of Breteuil was the capital of lower Normandy, Verneuil. The English continued their march on 4 July to Verneuil, seized it, looted it and took prisoner anyone whom it was considered might be worth a ransom. The richest men in the district had fortified themselves in Verneuil's strong keep with their families and valuables. The historian Alfred Burne hypothesises that French siege equipment had been captured at Pont-Audemer and made storming fortified places a more viable proposition than earlier in the , when they were avoided. In any event, the keep was assaulted; many English are recorded as being wounded, but none