Fraternitas is where the younger Titus Pullus finally becomes much more like his Avus - the original Titus Pullus. I missed the first Titus so much that I had trouble getting into the books that followed his death, but this one brings back a lot of the old Pullus spirit and I applaud the author for doing so. In Fraternitas, Rome is in the midst of the Pax Romana and there are no provinces being invaded by barbarians or civil wars to deal with. The legions must still march, however, and Titus and company find themselves marching through Pannonia mostly to keep the various tribes in line. In order to make things a bit more interesting, the Primus Pilus of Titus' unit decides to create a conflict by allegedly setting fire to a citizen's farm and blaming it on the local tribe, thus creating a reason to invade them. Of course the result of this is to raise the ire of the powers that be in Rome. The second half of the book involves Titus and his superiors being called to Rome for a tribunal to try the Primus Pilus for his role in the bogus invasion. I was particularly interested in the descriptions of the political machinations that occurred in ancient Rome.
This series has lost none of its luster. I have read them all so far and still look forward to the next release. I don't know how far the author plans to take this saga, but I hope it goes on for some time.