The root of the Hundred Years' War, now just about to commence, must be sought in the affairs of Guienne, and not in any of the other causes which complicated and obscured the outbreak of hostilities. These, however, were sufficiently important in themselves. The most obvious was the aid which Philip VI. had given to the exiled David Bruce, when he was driven out of Scotland by Edward and his ally Baliol. The English king replied by welcoming and harbouring Robert of Artois, a cousin whom Philip VI. had expelled from France. He also made alliances with several of the dukes and counts of the Netherlands, and with the emperor Louis the Bavarian, obviously with the intention of raising trouble for France on her northern and eastern frontiers.
It was Philip, however, who actually began the war, by declaring Guienne and the other continental dominions of Edward III. forfeited to the French crown, and sending out a fleet which ravaged the south coast of England in 1337. In return Edward raised a claim to the throne of France, not that he had any serious intention of pressing it--for throughout his reign he always showed himself ready to barter it away in return for sufficient territorial gains--but because such a claim was in several ways a useful asset to him both in war and in diplomacy. It was first turned to account when the Flemings, who had scruples about opposing their liege lord the king of France, found it convenient to discover that, since Edward was the real king and not Philip, their allegiance was due in the same direction whither their commercial interests drew them. Led by the great demagogue dictator, Jacob van Artevelde, they became the mainstay of the English party in the Netherlands.
Edward's claim--such as it was--rested on the assertion that his mother, Isabella, was nearer of kin to her brother Charles IV., the last king of the main line of the house of Capet, than was Charles's cousin Philip of Valois. The French lawyers ruled that heiresses could not succeed to the crown themselves, but Edward pleaded that they could nevertheless transmit their right to their sons. He found it convenient to forget that the elder brother of Charles IV., King Louis X., had left a daughter, whose son, the king of Navarre, had on this theory a title preferable to his own. This prince, he said, had not been born at the time of his grandfather's death, and so lost any rights that might have passed to him had he been alive at that time. A far more fatal bar to Edward's claim than the existence of Charles of Navarre was the fact that the peers of France, when summoned to decide the succession question nine years before, had decided that Philip of Valois had the sole valid claim to the crown, and that Edward had then done homage to him for Guienne. If he pleaded that in 1328 he had been the mere tool of his mother and Mortimer, he could be reminded of the unfortunate fact that in 1331, after he had crushed Mortimer, and taken the power into his own hands, he had deliberately renewed his oath to King Philip.
