In December, the French began to plan for war. Francis did not wish to openly attack Charles because Henry had announced his intention to intervene against the first party to break the tenuous peace. Instead, he turned to more covert support for incursions into German and Spanish territory. One attack would be made on the Meuse River, under the leadership of Robert de la Marck. Simultaneously, a French-Navarrese army would advance through Navarre after reconquering St-Jean-Pied-de-Port. The expedition was nominally led by the 18-year-old Navarrese king Henry d'Albret, whose kingdom had been invaded by Ferdinand II of Aragon in 1512, but the army was effectively commanded by André de Foix and funded and equipped by the French. The French designs quickly proved flawed as the intervention of Henry of Nassau drove back the Meuse offensive; and although de Foix was initially successful in seizing Pamplona, he was driven from Navarre after being defeated at the Battle of Esquiroz on 30 June 1521.