John had had him murdered. The outcry over Arthur's fate saw an increase in local opposition to John, which Philip used to his advantage. He took to the offensive and, apart from a five-month siege of Andely, swept all before him. After Andely surrendered, John fled to England. By the end of 1204, most of Normandy and the Angevin lands, including much of Aquitaine, had fallen into Philip's hands. What Philip had gained through victory in war, he sought to confirm by legal means. Philip, again acting as John's liege lord over his French lands, summoned him to appear before the Court of the Twelve Peers of France to answer for Arthur's murder. John requested safe conduct, but Philip only agreed to allow him to come in peace, while providing for his return only if it were allowed after the judgment of his peers. Not willing to risk his life on such a guarantee, John refused to appear, so Philip summarily dispossessed the English of all lands. Pushed by his barons, John eventually launched an invasion of northern France in 1206, disembarking with his army at La Rochelle during one of Philip's absences, but the campaign ended up a disaster. After backing out of a conference that he himself had demanded, John eventually bargained at Thouars for a two-year truce, the price of which was his agreement to the chief provisions of the judgment of the Court of Peers, including a loss of his patrimony. Alliances against Philip, 1208–1213 In 1208, Philip of Swabia, the successful candidate to become Holy Roman Emperor, was assassinated. As a result, the imperial crown was given to his rival Otto IV, the nephew of King John. Otto, prior to his accession, had promised to help John recover his lost possessions in France, but circumstances prevented him from making good on his promise. By 1212, both John and Otto were engaged in power struggles against Pope Innocent III: John over his refusal to accept the papal nomination for the archbishop of Canterbury, and Otto over his attempt to strip King Frederick II of Germany of the Kingdom of Sicily. Philip decided to take advantage of this situation, first in Germany, where he aided the German noble rebellion in support of the young Frederick. John immediately threw England's weight behind Otto, and Philip now saw his chance to launch a successful invasion of England. In order