The De Mercy family rose to increasing power during the middle ages in the region of what is now southern Belgium, Lorraine and Luxembourg. Lorraine can refer to: the independent Duchy of Lorraine and later French province of Lorraine: see Lorraine (province). ...

By the fifteenth century Jean de Mercy was lord of Clémarais (1422); in 1477, Roger de Mercy ("the Valiant") was appointed Captain and Provost of Longwy by Duke René II of Lorraine. The family progressively expanded their domain, incorporating parts of Aix-sur-Cloie, Battincourt and Piémont. A castle named Claimaraix is mentioned in a document dated 3 March 1612, as a possession of Anne de Landres, widow of Jean de Mercy. By the sixteenth century they owned substantial land near Esch, including the castle at Mittenthal and the important mill at Bergem. Longwy is a town and commune located in the Meurthe-et-Moselle département in northeastern France. ... Lorraine can refer to: the independent Duchy of Lorraine and later French province of Lorraine: see Lorraine (province). ... Bergem (Luxembourgish: Biergem) is a town in the commune of Mondercange, in south-western Luxembourg. ...

The inheritance of Count Claudius Florimund de Mercy (1666-1734), Imperial field marshal, (born at Longwy in Lorraine) passed to the Counts d'Argenteau. Important scions of the family include:

Florimond Claude, comte de Mercy-Argenteau (1727–1794), Austrian diplomat, son of Antoine, comte de Mercy-Argenteau, who arranged the marriage of Louis XVI to Marie Antoinette.

Archbishop Marie-Charles-Isidore de Mercy, 1736-1811, Bishop of Lucon 1775-1801; Archbishop of Bourges, 1802-1811

Eugène Arnould Henri Charles François Marie, comte de Mercy-Argenteau (22 Aug. 1838-2 May 1888). Husband of the musician Marie-Clotilde-Elisabeth Louise de Riquet, comtesse de Mercy-Argenteau, a collaborator with Franz Liszt. Marie-Clotilde-Elisabeth Louise de Riquet was born on 3 June 1837 as Comtesse de Caraman-Chimay. ... Franz Liszt (Hungarian: Liszt Ferenc) (October 22, 1811 – July 31, 1886) was a Hungarian virtuoso pianist and composer. ...