A narrative genealogical history of the Rees family of Cilymaenllwyd, Carmarthenshire, tracing their lineage across fourteen centuries from the sixth-century warrior king Urien Rheged, through a Crusader knight of the Holy Sepulchre, to the magistrates and High Sheriffs of Georgian Wales. The centrepiece of the story is John Rees, born 1781, who served as a Royal Navy midshipman at three of the defining engagements of the age of sail the Helder Expedition (1799), the Battle of Camperdown (1797), and the Battle of Copenhagen (1801), the last aboard HMS Ardent. He returned to Carmarthenshire on the Peace of Amiens in 1802 to inherit Cilymaenllwyd and marry Anne-Catherine Vanderhorst, daughter of the American Consul at Bristol, whose own family descended from a Dutch officer in William of Orange's fleet and produced the Governor of South Carolina. The article also reveals an unexpected historical connection between the Rees family's judicial authority in Carmarthenshire and the Emanuel family of Pembrey, whose ancestor William Emanuel was tried and gibbeted in 1788 following an investigation authorised by John Rees Senior. Sourced from Burke's Landed Gentry, 1845.