The title of Viscount Molesworth was created in the Peerage of Ireland in 1716. The Viscount bears the subsidiary title of Baron Philipstown (1716), also in the Peerage of Ireland.
ROBERT MOLESWORTHMOLESWORTH, 1ST VISCOUNT (1656-1725), came of an old Northamptonshire family.
He was succeeded by his two sons, John, 2nd viscount (1679-1726), and Richard 3rd viscount (1680-1758), the latter of whom saved Marlborough's life at the battle of Ramillies and rose to be a field-marshal.
The 3rd viscount's son Richard Nassau (1748-1793) succeeded to the title, which has descended accordingly.