Gustav IV Adolph, King of Sweden 1792-1809, was the son and successor of King Gustav III. His hatred of Napoleon led him in 1805 to declare war on France and he abandoned Swedish neutrality. After several ill-fated political manoeuvres, he was arrested in a military coup and forced to abdicate in 1809. He was exiled with his wife Queen Frederike of Baden and their children but divorced his wife in 1812 and spent 25 years travelling in Europe before dying in St Gallen. He was succeeded by his uncle King Charles XIII. The present miniature was painted in the year of his marriage to Friederike (1781-1826), daughter of Karl Ludwig, Hereditary Prince of Baden.
For further signed miniatures by Gillberg of the same sitter, see M. Olausson and J. Sjöholm, Nationalmuseum Stockholm. Svenska och övriga nordiska miniatyrer, Halmstad, 2001, I, pp. 199 and 211.