Original: -- 29 January 1820 [ N.S. ] ) was King of Great Britain and King of Ireland from 25 October 1760 until the union of these two countries on 1 January 1801 , after which he was King of the United Kingdom of Great Britain and Ireland until his death .
Simplified: George III ( Born George William Frederick June 4 , 1738 - January 29 , 1820 ) was King of Great Britain and King of Ireland from October 25 , 1760 until January 1 , 1801 .