Charles IX. to allay the
excitement created by the massacre of St Bartholomew, and the same year
he was sent to Germany and Switzerland. Two years later he was
reappointed by Henry III. ambassador to Queen Elizabeth, and he remained
at her court for ten years. During this period he used his influence to
promote the marriage of the queen with the duke of Alencon, with a view
especially to strengthen and maintain the alliance of the two countries.
But Elizabeth made so many promises only to break them that at last he
refused to accept them or communicate them to his government. On his
return to France he found that his chateau of La Mauvissiere had been
destroyed in the civil war; and as he refused to recognize the authority
of the League, the duke of Guise deprived him of the governorship of
Saint-Dizier. He was thus brought almost to a state of destitution. But
on the accession of Henry IV., the king, who knew his worth, and was
confident that although he was a Catholic he might rely on his fidelity,
gave him a command in the army, and entrusted him with various
confidential missions.

Castelnau died at Joinville in 1592. His _Memoires_ rank very high among
the original authorities for the period they cover, the eleven years
between 1559 and 1570. They were written during his last embassy in
England for the benefit of his son; and they possess the merits of
clearness, veracity and impartiality. They were first printed in 1621;
again, with additions by Le Laboureur, in 2 vols. folio, in 1659; and a
third time, still further enlarged by Jean Godefroy, 3 vols. folio, in
1731. Castelnau translated into French the Latin work of Ramus, _On the
Manners and Customs of the Ancient Gauls_. Various letters of his are
preserved in the Cottonian and Harleian collections in the British
Museum.

His grandson, JACQUES DE CASTELNAU (1620-1658), distinguished himself in
the war against Austria and Spain during the ministries of Richelieu and
Mazarin, and died marshal of France.

See Hubault, _Ambassade de Castelnau en Angleterre_ (1856); _Relations
politiques de la France ... avec l'Ecosse au seizieme siecle_, edited
by J.B.A.T. Teulet (1862); and De la Ferriere, _Les Projets de mariage
d'Elisabeth_ (1883).

CASTELNAUDARY, a town of south-western France, capital of an
arrondissement in the department of Aude, 22 m. W.N.W. of Carcassonne,
on the Southern railway between that city and Toulouse. Pop. (1906)
6650. It is f