He had the misfortune to be present at two military debacles of the Napoleonic Wars, the second invasion of the Río de la Plata and the Walcheren Campaign, and while he was not personally implicated in either, he saw no further notable military service. Mahon succeeded his father as Lord Hartland in 1819 and died without issue in 1835, his title and estates passing to his youngest brother.
He encountered misfortune by being present at two military failures of the Napoleonic Wars: the second invasion of the Río de la Plata and the Walcheren Campaign. Despite not personally contributing to either, he did not serve in any notable military capacity afterward. Mahon succeeded his father as Lord Hartland in 1819 and died without issue in 1835, with his title and estates passing to his youngest brother.