The Jesuit Guy Tachard (1648–1712) first came to Siam
with the Chaumont-Choisy embassy of 1685 as one of
six Jesuits destined for missionary work in China.
The group was headed by Fr de Fontaney (1643–1710).
The decision of the Abbé de Choisy (1644–1724), who
held the post of coadjutant ambassador, to withdraw
from the diplomatic scene and effect a retreat prior
to his ordination as a priest in Lopburi on 10
December 1685 enabled Tachard to replace him as
interpreter of Phaulkon (c.1647–1688), the
influential Levantine adventurer then holding the
functions, though not the title, of minister of
trade and foreign affairs (phra
khlang) for King Narai (r.1656–1688).
Tachard was then charged with secret negotiations
with the court of Louis XIV, most particularly with
Fr de La Chaize, the king's Jesuit confessor, and
the Marquis de Seignelay, the secretary of state for
the navy, to negotiate the lease of a port and the
dispatch of persons of rank to occupy key posts in
the Siamese kingdom. In Paris, he lost no time in
publishing his account of the first French embassy
to Siam, padding it with unacknowledged extracts
from one of the other Jesuits in his party, Fr de
Bouvet.