 He had previously obtained extensive territorial possessions from the crown, particularly a grant of various lands in county Longford, in all , which were erected into the manor of Castle Forbes, with the usual manorial privileges.A lieutenant-colonel, he had accompanied his regiment to assist King Gustavus Adolphus of Sweden, but was killed in a duel at Hamburg in 1632.Forbes married after February 1618, Janet (d. after Sept 1642), daughter of Maurice Lauder of Belhaven and West Barns (d. 1602), Member of Parliament for and Baillie and Burgess of, Dunbar, by his third wife Alison Cass.