George III of the United Kingdom did not experience Great Britain as a dominant European power.
George III ( George William Frederick ; 4 June 1738 -- 29 January 1820 ) was King of Great Britain and Ireland from 25 October 1760 until the union of the two countries on 1 January 1801 , after which he was King of the United Kingdom of Great Britain and Ireland until his death . Early in his reign , Great Britain defeated France in the Seven Years ' War , becoming the dominant European power in North America and India .