Why did king edward the third think he had the right to the french throne? and how did the people feel about this? (hundred years war)

From the 1340s to the nineteenth century, barring two brief interims during the 1360s and the 1420s, the lords and rulers of England (and, later, of Great Britain) likewise guaranteed the position of the royalty of France. The case dates from Edward III, who guaranteed the French position of royalty in 1340 as the sororal nephew of the last immediate Capetian, Charles IV. Edward and his beneficiaries battled the Hundred Years' War to implement this case and were quickly fruitful during the 1420s under Henry V and Henry VI, yet the House of Valois, a cadet part of the Capetian tradition, was, at last, successful and held control of France. Regardless of this, English and British rulers proceeded to unmistakably call themselves rulers of France and the French fleur-de-lys were incorporated into the regal arms. This proceeded until 1801, by which time France never again had any ruler, having turned into a republic. The Jacobite petitioners, in any case, did not unequivocally surrender the case.

of what agreement it does not show