Helenum, Priami filium, regno Epiri potitum esse atque Andromachen, viduam Hectoris, uxorem duxisse! Aeneas, cum a viro ipso certior fieri cuperet, classe in portu relicta ad urbem progrediebatur.
Basically you are right. However, classe in portu relicta
is an ablative absolute which - to me at least - seems to indicate merely circumstances of lesser importance. Aeneas did not leave the fleet in the harbour in order to traverse the city. Of course, he has to do so to be able to traverse the city (theoretically he might raze the town and draw the ships on shore and all along to the dwelling place of Helenus
. But the traversal is only a means. Therefore I would rather say: Aeneas classem in portu reliquit et ad urbem progrediebatur ut cum Heleno loqueretur...