When did Lord North's military collapse and Britain's whigs take power?

Lord North's military collapse occurred around 1781, particularly marked by the British defeat at the Siege of Yorktown in October of that year, which significantly weakened British efforts in the American Revolutionary War. Following this military setback, the political landscape in Britain shifted, leading to the rise of the Whigs. By 1782, the Whigs, under leaders like Charles James Fox and Lord Rockingham, gained prominence and effectively took power, culminating in North's resignation and the formation of a new government.