Is anyone else dying to get to Garlemald?

[YianKutku]

Those Castri did not even exist before the Calamity though - there was only a single castra established in Eorzea in the Sixth Astral Era located in Mor Dhona (Castrum Novus), that was Nael van Darnus's base of operations. Castrum Novus was destroyed in the Calamity, being sited right next to Carteneau, and following that when Gaius and the XIVth seized land throughout Eorzea to build new castri he simply took over what was left of Castrum Novus and rebuilt it into a new castra, renaming it in the process (Castrum Centri).

It's highly likely the surviving VIIth troops, if any, were simply absorbed into the XIVth, but it's equally likely they all died at Carteneau, given their zealous devotion to Nael.

I'm going to do some tea-leaf reading on the specific language used in the lorebook:

Meanwhile, having watched the battle unfold from the deck of an imperial airship, Legatus Gaius van Baelsar, commander of the XIVth Legion, saw an opportunity. Upon withdrawing to Ala Mhigo with the remainder of his fleet, he sent troops to Mor Dhona's Castrum Novum, with orders to execute the remnants of van Darnus's VIIth Legion and secure the fortress for the XIVth. From there they dispatched cohorts to La Noscea, Thanalan, the Black Shroud, and Coerthas, and upon the lands they claimed were built many new castra.

So we know that there were still members of the VIIth Legion at Castrum Novum, and enough of it was still standing for the XIVth to "secure". It is also implied from the wording that Castrum Novum, to be renamed Castrum Centri, was not considered one of the "many new castra".

If we're being totally pedantic, it might be more accurate to say that Gaius believed there were still members of the VIIth etc, and he gave orders with that belief.

(Completely unrelated, but we do meet a few survivors of the VIIth Legion. Apart from Kan-E-Senna's bodyguard, there's also the deserter living near Wineport. And then there are the deserter's former comrades, who tried to kill him. It is implied that apart from Kan-E-Senna's bodyguard, none of them are altogether sane anymore.)

One bit that does puzzle me is where the lorebook includes the Black Shroud as one of the places a new castrum was built. The only castrum in the Shroud is Castrum Oriens, which to my recollection is built around Baelsar's Wall. As in Baelsar's Wall is effectively part of Castrum Oriens, or Castrum Oriens is part of Baelsar's Wall; they're basically synonymous.

In the lorebook map, however, Castrum Oriens is built on the Shroud side of Baelsar's Wall. I suppose we can blame simplified map stylism, but it would be odd for Baelsar's Wall, built soon after the Battle of Silvertear Skies, to not have a castrum built into it, simply for defence. A static wall isn't very much deterrence, after all.