Why were the Angevin lands in France a threat to Philip II Augustus?

The Angevin lands—which included Normandy, Maine, Anjou, Touraine, and Aquitaine—posed a constant threat to Philip II Augustus because their concentration in the hands of the English kings created a power imbalance that undermined the French monarchy.12

While these territories were technically held as fiefs from the king of France, the English kings possessed direct control over a vast expanse of land that far exceeded the size of the French royal domain. This concentration of power allowed the English rulers to exert significant influence and military pressure within France, effectively encircling the royal domain and acting as a persistent menace to its security and sovereignty. Philip II recognized that as long as these territories remained under English control, the French crown’s authority remained limited and vulnerable, prompting his long-term efforts to dismantle the Angevin Empire.213