George IV of the United Kingdom

When George III became temporarily insane, the Prince of Wales (future George IV) sought to become regent. The crisis ended when the king recovered, but it established a precedent for parliamentary control over regency.

Following George III's final mental collapse, the Prince of Wales was formally appointed Prince Regent under the Regency Act 1811. He exercised royal powers for nine years while his father lived in seclusion.

As Prince Regent, George IV commissioned John Nash to design Regent Street, Regent's Park, and the Royal Pavilion in Brighton. His patronage defined the architectural and cultural style of the Regency period.

Upon George III's death, the Prince Regent became King George IV. His accession was marred by his attempt to divorce Queen Caroline, leading to a public scandal and the Pains and Penalties Bill of 1820.

George IV became the first British monarch to visit Ireland since the Acts of Union. The visit aimed to promote loyalty but was overshadowed by the ongoing Catholic Emancipation debate.

George IV reluctantly signed the Roman Catholic Relief Act 1829, granting Catholic Emancipation. He had opposed the measure but yielded to Prime Minister Wellington's threat of resignation.