I'm far from being an historian, but I have read the Du Guesclin biography by Georges Minois (http://www.fayard.fr/du-guesclin-9782213028538)

The author think that the very concept of nation ( and nationalism ) was non-existent during early medieval era, but that it started to appear during the Hundred Years War, especially through figures like DuGuesclin and Jeanne d'Arc.

It seems than peoples would think as them as coming from a village, city, or from a community, under the dominion of the local chief of fiefdom (knight, noble, ecclesiastic...). And they had a general idea of who was the actual King, but loyalties changed too often between your lord and his peers for you to really identify yourself as part of a country more than from a particular city/village. You had a feudal lord, not a country.

It was even very uncommon for troops and mercenary band to remain loyal to the same Lord.

Then during the early Hundred Year wars, Charles V used the indefectible loyalty of Du Guesclin to the Crown of France to bring the concept of nationalism in France, and push more loyalty in his subjects. It proved really efficient in many way, and it is even probable that the whole Jeanne d'Arc event was a huge communication operation to push further the concept.

So when the war was close to the end, area that pledged loyalties to House of Plantagenet were maybe seeing themselves as allies, or under the dominion of a feudal lord allied to the House of Plantagenet, but still not part as a Kingdom or a nation, when however, the sentiment of nationalism was rising under the rule of the Valois House, and the concept of France as a nation appearing slowly thanks to, well let's say new public relation management methods ( Jeanne d'Arc and all this ).

Sorry for my English i'm French. A real historian could precise or correct me if i'm wrong, but I still recommend you this book, its an interesting read.