The Regency in the United Kingdom of Great Britain and Ireland was a period at the end of the Georgian era, when King George III was deemed unfit to rule due to his illness, and his son ruled as his proxy, as prince regent. Upon George III's death in 1820, the prince regent became King George IV. The term Regency (or Regency era) can refer to various stretches of time; some are longer than the decade of the formal Regency, which lasted from 1811 to 1820. The period from 1795 to 1837, which includes the latter part of George III's reign and the reigns of his sons George IV and William IV, is sometimes regarded as the Regency era, characterised by distinctive trends in British architecture, literature, fashions, politics, and culture.