Edward spent much of his reign reforming royal administration and common law. Through an extensive legal inquiry, he investigated the tenure of various feudal liberties, while the law was reformed through a series of statutes regulating criminal and property law. Increasingly, however, Edward's attention was drawn towards military affairs. After suppressing a minor rebellion in Wales in 1276–77, Edward responded to a second rebellion in 1282–83 with a full-scale war of conquest. After a successful campaign, he subjected Wales to English rule, built a series of castles and towns in the countryside and settled them with English people. Next, his efforts were directed towards the Kingdom of Scotland. Initially invited to arbitrate a succession dispute, Edward claimed feudal suzerainty over Scotland. The war that followed continued after Edward's death, even though the English seemed victorious at several points. Simultaneously, Edward found himself at war with France (a Scottish ally) after King Philip IV of France had confiscated the Duchy of Gascony, which until then had been held in personal union with the Kingdom of England. Although Edward recovered his duchy, this conflict relieved English military pressure against Scotland. At the same time there were problems at home. In the mid-1290s, extensive military campaigns required high levels of taxation, and Edward met with both lay and ecclesiastical opposition. These crises were initially averted, but issues remained unsettled. When the King died in 1307, he left to his son Edward II an ongoing war with Scotland and many financial and political problems.