Yes, I think there was a Servilii Caepiones involved in some funny business there. But, were there fortifications involved?
Seems to me that the Celts and Germans were no good when attacking walled cities. But I'm happy to be corrected if I'm wrong.
That would be one Quintus Servilius Caepio, a patrician of awesome hauter who refused to combine his pro-consular legions with those of the consul Gnaeus Mallius Maximus, a new man whose cognomen was more awesome than his list of accomplishments to that point. Both armies were caught unprepared for battle and destoyed in detail, supposedly while in legionary camps. It's worth noting that this was the crisis that precipitated Gaius Marius being elected Consul five consecutive times, leading to the institutionalization of the Marian reforms to the legionary organization.
It's also worth noting that most of the Germanic success against Rome came versus armies who were either poorly led or caught with their guard down. Most of the reasons for the great success of Gaius Marius in all of his battles can be boiled down to leadership. He was not a political appointee. In can be said that Marius achieved his military commands in spite of his political skills! It is very doubtful that a man like Gaius Marius, a talented leader who had worked his way up through the military ranks, would suffer incompetent political apointees to officer his legions, so one may reasonably suppose the Marian led legions were more competently led and trained. Marius was fully prepared for his battles in the German campaign, and one may presume that his operational plans were carried out efficiently by his subordinates.
As to Celts and Germans being no good at attacking walled cities, I'm sure the occupants of Rome during the Gallic invasion by Brennus would beg to differ, not to mention the denizens of Rome present for Alaric's party some centuries later!