He succeeded his brother to the title of
Duke of Argyll in October 1743. During the
Jacobite rising of 1745 he was an important pro-government political figure in Western Scotland and used his clan power, militia forces, and administrative authority to organise government forces against the Jacobites. He worked on
Inveraray Castle, his brother's estate, which was finished in the 1750s; however, he never lived in it, and he died in 1761. He is buried at
Kilmun Parish Church. He was married to Anne Whitfield about 1712, but had no legitimate male issue at his death. In his will, he left his English property to his mistress Ann (née Shireburn) Williams. His titles passed to his cousin,
John Campbell, 4th Duke of Argyll, the son of his father's brother
John Campbell of Mamore. The Duke established an estate at
Whitton Park,
Whitton in
Middlesex in 1722 on land that had been enclosed some years earlier from
Hounslow Heath. The Duke was an enthusiastic gardener and he imported large numbers of exotic species of plants and trees for his estate. He was nicknamed the "Treemonger" by
Horace Walpole. On his death, many of these, including mature trees, were moved by his nephew,
John Stuart, 3rd Earl of Bute, to the
Princess of Wales' new garden at Kew. This later became
Kew Gardens and some of the Duke's trees are still to be seen there to this day. The
Duke of Argyll's Tea Tree is an imported shrub named after him which has become established in hedgerows in some parts of England. ==In literature ==