It is interesting that Vortigern would be called the Dux Britannicum or a Comes Littoris Saxonici considering how these titles were subordinate titles given to men who ruled beneath the Comes Britanniae. This 'Count of Britain' was the supreme military authority of the entire island and had a roving commision to defend the country against foreign invaders.

According to Professor Rhys, the Dux Britanniarum had charge over the northern wall while the Comes Littoris Saxonici guarded the south-eastern coasts, or more specifically, the Saxon Shore which is now known as Kent. If this is the case, it would appear to me that Vortigern would have been more aptly known as the Count of Britain where Guoirancgon would have probably been more or less a subordinate of Vortigern and was more or less a governor of the Ceint province.

Diantha noted the quote from Ward which states,

"Had Guoirancgon been truly a king of the Cantii, or even a local chieftain, this would have been unthinkable. Yet no effort was made to recover his place, no rebellion on the part of the betrayed civitas is recorded, no question is even raised about Vortigern's right so to treat his Kentish sub-ruler. Guoirancgon merely disappears from the scene."

Unfortunately from the works of Gildas and Bede, we don't see any rebellions that cropped up, but the Saxons seem to have kept a better record of battles that occured in this area. We are told through the Anglo Saxon Chronicles that the province of Kent was given to the Saxons in 449. But we do not see the Britons simply just give the land away that easy. We are told that 5 years later, "A.D. 455. This year Hengest and Horsa fought with Wurtgern the
king on the spot that is called Aylesford. His brother Horsa
being there slain, Hengest afterwards took to the kingdom with
his son Esc."

Now the question remains of who Wurtgern was. Was he in fact the same Wurtgern who invited the Saxons into Britain, or was he a different ruler? This confusion of names complicates things greatly because the Chronicles clearly identifies the two as clearly different men.

Also, we see that there was another rebellion in 457 in which "The Britons then forsook the land of Kent, and in great
consternation fled to London". Just from the duration of the time when the Saxons were first invited into Britain and the time of the last battle, a duration of seven years, we can infer that there were most likely a series of minor battle fought here.

It is interesting to find inconsistencies in historical documents, but frustrating none the less. As Diatha said though, we may find out the truth if we keep plugging away.