 thumb|right|300px|robert stewart, viscount castlereagh, british foreign secretary, who became the second marquess of londonderry in 1821 thumb|right|200px marquess of londonderry, of the county of londonderry ( ) is a title in the peerage of ireland. it was created in 1816 for robert stewart, 1st earl of londonderry. he had earlier represented county down in the irish house of commons. stewart had already been created baron londonderry in 1789, viscount castlereagh, of castlereagh in the county of down, in 1795 and earl of londonderry, of the county of londonderry in 1796. these titles are also in the peerage of ireland. he was the son of alexander stewart, who had married mary cowan, sister and heiress of robert cowan, who gained great wealth as governor of bombay from 1729 to 1737. alexander was from ballylawn, a townland at the south-west corner of inishowen in the north of county donegal, a county located in the west of ulster in the northern part of ireland. however, much of the stewart family wealth was based on the estates which came into the family through this marriage. the 1st marquess was one of the few people to become a marquess without inheriting any titles prior to the creation. he sat in the british house of lords as one of the twenty-eight original irish representative peers from 1800 to 1821. he was succeeded by his son from his first marriage to lady sarah seymour. the 2nd marquess, better known as lord castlereagh (he went by the courtesy title of viscount castlereagh from 1796 to 1821), was a noted statesman and diplomat. castlereagh is best remembered for his tenure as foreign secretary of the united kingdom from 1812 to 1822 and played an important role at the congress of vienna of 1814 to 1815. he committed suicide in 1822, one year after succeeding his father in the marquessate. the 2nd marquess did not follow his father as a representative peer into the house of lords, this permitted him to continue fulfilling his roles in the house of commons. castlereagh was succeeded by his half-brother, the 3rd marquess. he was the only son from the 1st marquess's second marriage to lady fr
Marquessates_in_the_Peerage_of_Ireland Vane-Tempest-Stewart_family