otland he passed into England, and treated with Queen Elizabeth
respecting her claims on Calais (1559), a settlement of which was
effected at the congress of Cateau-Cambresis. He was next sent as
ambassador to the princes of Germany, for the purpose of prevailing upon
them to withdraw their favour from the Protestants. This embassy was
followed by missions to Margaret of Parma, governess of the Netherlands,
to Savoy, and then to Rome, to ascertain the views of Pope Paul IV. with
regard to France. Paul having died just before his arrival, Castelnau
used his influence in favour of the election of Pius IV. Returning to
France, he once more entered the navy, and served under his former
patron. It was his good fortune, at Nantes, to discover the earliest
symptoms of the conspiracy of Amboise, which he immediately reported to
the government.

After the death of Francis II. (December 1560) he accompanied the queen,
Mary Stuart, to Scotland, and remained with her a year, during which
time he made several journeys into England, and attempted to bring about
a reconciliation between Mary and Queen Elizabeth. The wise and moderate
counsels which he offered to the former were unheeded. In 1562, in
consequence of the civil war in France, he returned there. He was
employed against the Protestants in Brittany, was taken prisoner in an
engagement with them and sent to Havre, but was soon after exchanged. In
the midst of the excited passions of his countrymen, Castelnau, who was
a sincere Catholic, maintained a wise self-control and moderation, and
by his counsels rendered valuable service to the government. He served
at the siege of Rouen, distinguished himself at the battle of Dreux,
took Tancarville, and contributed in 1563 to the recapture of Havre from
the English.

During the next ten years Castelnau was employed in various important
missions:--first to Queen Elizabeth, to negotiate a peace; next to the
duke of Alba, the new governor of the Netherlands. On this occasion he
discovered the project formed by the prince of Conde and Admiral Coligny
to seize and carry off the royal family at Monceaux (1567). After the
battle of St Denis he was again sent to Germany to solicit aid against
the Protestants; and on his return he was rewarded for his services with
the post of governor of Saint-Dizier and a company of orderlies. At the
head of his company he took part in the battles of Jarnac and
Moncontour. In 1572 he was sent to England by