A brief somewhat ret-conned history of Montaigne:

In 1661, the King of Montaigne invited the Heirophant to come to
Charouse to resolve certain issues that had arisen that strained the
relationship of the church to the Montaignian government.  Among the
issues were 1) the right of the state to try clergy under secular law
instead of under papal law, 2) the right of the state to tax clergy and
church holdings, and 3) the right to practice sorcery.  While visiting,
however, the Heirophant (as you now know) was murdered.  Publically,
Louis declared that before his death, the Heirophant had renounced
Cardinal Verdugo and his faction, and sided with the Montaignian
cardinals who had, of course, pretty much agreed with Louis on all three
points.  Louis declared himself "L'Empereur", and began openly
practicing sorcery.  He called for a meeting of Cardinals to be held in
Avignon to elect a new Heirophant.  Cardinal Verdugo countered by
calling for his own meeting in Vaticine city.  Both meetings ended up
boycotted by the other group of cardinals, but neither went so far as
to actually declare a new Heirophant, a fact that Louis originally found
vexing but has since found useful.  Both groups took the opportunity to
re-organize, and it is believed that it was at that first meeting that
Cardinal Verdugo first broached the idea of using the Castillian army to
'convert' the heretics in Montaigne by force.  It took him four years to
rally enough support to do so, but in 1665 the invasion took place.

Montegue had been a high-ranking officer in Louis' army, but was known
for being extremely devout. Louis and the Avignon cardinals had sent him
to the Crescent Empire on a sort of mini-crusade in 1662. Montegue
returned successfully from that mission in 1664, to the surprise of
many. His success greatly heartened the people of Montaigne, who saw it
as divine vindication of the Avignon Cardinals--no small matter, since
by that time each group had declared the other heretics, and consigned
their followers to Legion. Louis placed him in the high-status but
relatively low-importance position of Captain of the King's Guard. That
position proved to be crucial in the Castillian invasion, however, as
Montegue turned the last line of defense into a brilliant victory, and
Louis made him High General of the Montaignian army. From here, the
events basically follow that in the book, though they take a bit longer:
Montegue led the army into Castille and took over the west half of the
nation over the course of a 2-year conquest. Just as the army was
finishing taking over the western penninsula, however, Louis recalled
Montegue, split his army, and sent a quarter of the army with him to
Ussura.

Our Two Fops had pieced together the last bit from information at the
embassy.  At this point, working out the above history and talking with
the rest of the party, they can realize something else:  they left
Montaigne in June ('Sextus') of 1667.  The rest of the party left Eisen in
December ('Decimus') of 1667, and Montegue had already begun his invasion
at that point (let's say September/'Septimus').  It's now January
('Primus').  That's... a lot longer travel time for the fops than for the
rest of the group.