George III (George William Frederick) (4 June 1738 – 29 January 1820) was King of Great Britain and King of Ireland from 25 October 1760 until 1 January 1801, and thereafter King of the United Kingdom of Great Britain and Ireland until his death. He was concurrently Duke of Brunswick-Lüneburg, and thus Elector (and later King) of Hanover. The Electorate became the Kingdom of Hanover on 12 October 1814. George was the third British monarch of the House of Hanover, but the first to be born in
Britain and use English as his first language. In fact, he never even visited Germany. During George III's reign, Britain lost many of its colonies in North America, which became the United States. Also during his reign, the realms of Great Britain and Ireland were joined together to form the United Kingdom.
Later in his reign George III suffered from recurrent and, eventually, permanent mental illness. It has been popularly speculated that he suffered from the blood disease porphyria, along with other British monarchs. Recently, owing to studies showing high levels of the poison arsenic in King George's hair, arsenic is also thought to be a possible cause of King George's insanity and health problems. After a final relapse in 1811, George's eldest son, George, Prince of Wales ruled as Prince Regent. Upon George's death, the Prince of Wales succeeded his father as George IV.
George III has been nicknamed Farmer George, for "his plain, homely, thrifty manners and tastes" and because of his passionate interest in agriculture