A brief lull in hostilities allowed Pitt to concentrate effort on Ireland, where there had been an uprising and attempted French landing in 1798. In 1800, the British and Irish Parliaments passed an Act of Union that took effect on 1 January 1801 and united Great Britain and Ireland into a single state, known as the "United Kingdom of Great Britain and Ireland". George used the opportunity to abandon the title "king of France", which English and British Sovereigns had maintained since the reign of Edward III. It was suggested that George adopt the title "Emperor of the British Isles", but he refused. As part of his Irish policy, Pitt planned to remove certain legal disabilities that applied to Roman Catholics. George III claimed that to emancipate Catholics would be to violate his coronation oath, in which Sovereigns promise to maintain Protestantism. Faced with opposition to his religious reform policies from both the King and the British public, Pitt threatened to resign. At about the same time, the King had a relapse of his previous illness, which he blamed on worry over the Catholic question. On 14 March 1801, Pitt was formally replaced by the Speaker of the House of Commons, Henry Addington. Addington opposed emancipation, instituted annual accounts, abolished income tax and began a programme of disarmament. In October 1801, he made peace with the French, and in 1802 signed the Treaty of Amiens.