At dawn on 12 July 1346, a vast armada of ships appeared off the coast of Normandy. Their destination was St Vaast-la-Hougue, a small port on the north-eastern corner of the Cotentin peninsula. The size of the fleet and the presence of ships bearing the quartered leopards and lilies of the royal arms of England indicated that this was no mere raid. In fact, it was to be the largest amphibious operation of the Hundred Years War, and it had achieved complete surprise. The consternation of the local population can easily be appreciated. Robert Bertran, Marshal of France and commander on the spot, was able to muster a few hundred men. But since, according to an English narrative, a force of five hundred Genoese crossbowmen, their pay in arrears, had withdrawn from the area a few days previously, it is small wonder that the English met only light resistance as they landed and moved inland. It took several days to disembark the horses and supplies, during which time flying columns ranged across the Cotentin peninsula. Barfleur, a town ‘as good and large as Sandwich’, was burnt. ‘The men-at-arms of the region have withdrawn into the castles and fortified towns,’ noted Bartholomew Burgherssh in his report of 17 July. ‘There is no one left in the surrounding countryside for twenty miles around who is offering resistance,’ added Thomas Bradwardine in his letter of the same day. It had been an auspicious opening for the English, and on Tuesday, 18 July Edward III and his army set out from La Hougue and began the campaign proper. The king's intention, reported Burgherssh, was ‘to secure his rights by conquest’.

A good deal is known about the six-week campaign that followed. An itinerary for Edward III's march across Normandy can be established from a combination of administrative records and fourteenth-century narratives. (See Map 1.) Eyewitness accounts and contemporary secondary sources provide much detail, from a variety of perspectives, on many of the engagements that took place along the English line of march – from the skirmishes in the Cotentin, through the storming of a series of towns, most notably Caen on 26 July, to the climactic encounter at Crécy-en-Ponthieu on 26 August. With the exception of the week or so leading up to Crécy, reconstructing the sequence of major events presents few problems.