I just posted this on BGG as well, but thought I would post here for the benefit of FFG and anyone working on the Britannia FAQ.
The rules for the Romans moving out of an area controlled by a nation that has just submitted to them are as followed:
Any Roman armies stationed in an area held by a subject nation when submission is declared must move immediately to any adjacent Roman-occupied area(s); if there are none, they can move ta any adjacent vacant area(s). If after either of these movements they are in an area with a fort, they can take advantage of Roman road movement to move farther
It turns out that, with this wording, the rule can be used to allow the Romans to capture territory that they otherwise could not possibly reach so long as they set up to do it in a very "gamey" and unsatisfying-feeling way.
The situation is something like this.
The Brigante have already submitted to the Romans; say the Picts have formed a line of defense in Dalriada-Alban-Mar, and hold no other territories (they are planning to submit as soon as the Romans hit them and move back into the empty territories of Skye and Moray). Dunedin is empty, Strathclyde is occupied by the submitted Brigante.
The Romans send an army using Roman roads THROUGH the Brigante WITHOUT capturing Dunedin and attack Dalriada. The Picts announce their submission.
There is no Roman-occupied area adjacent to Dalriada; therefore, by the rule above, the Romans may move to any vacant adjacent area. Since Skye is adjacent to Dalriada and vacant, the Romans can now "hop" the Pict line and go there - even though they could not possible have reached Skye any other way, since the Difficult Terrain in Dalriada and Alban would normally stop their movement.
They can do similar things in submitting the Welsh, so long as they attack the Welsh by over-running the Belgae or Brigante and announce the Welsh fights BEFORE resolving the over-run fights.
Now, there's nothing wrong structurally with this rule; however, it FEELS immensely unsatisfying that the only reason the Romans are allowed to hop the Pict line (in the example given) is because they DON'T have a fort in Dunedin; if, God forbid, they'd put one there, all of a sudden Skye is inaccessible to them again.
Therefore, the question is, is this really the intent of this particular rule?