The Fort makes use of the little certain information we do possess. Trajan’s First Dacian War imposed a treaty on Decebalus, including a ban on hiring Roman deserters and on seeking allies. It also resulted in the establishment of Roman garrisons within his kingdom, mainly in the lowlands and the valleys leading to and from passes in the Carpathians. There was a Roman detachment at Decebalus’ capital of Sarmizegethusa Regia and part of its substantial defensive wall has been excavated, although the details of the post are not very well understood.

The peace proved temporary and there is a fair chance that both sides prepared for hostilities long before they resumed. One of the most visible signs of this was the great bridge across the Danube, which was opened by the end of AD 105 and part of a wider programme improving communications in the area. The base of only one pier remains to this day, but confirms the scale of the project, which was described in some detail by Dio and is depicted on Trajan’s Column. Trajan left Rome for the Danube on 4 June AD 105, so that much of the campaigning season was already spent before he arrived in the theatre of operations, and it looks as if he was taken by surprise. Trajan’s Column also shows a number of Roman forts under Dacian attack before the emperor arrives, while Dio told the story of the capture of Longinus. Rather than be used as a pawn in negotiations, the Roman officer committed suicide, using poison obtained by a freedman. The narrative does not make clear whose freedman this was, but claims that Decebalus demanded his return after the man escaped, offering his remaining Roman hostages as payment. Trajan refused.

The Fort takes these fragments and depicts an uneasy peace with men on both sides anticipating a renewal of war and trying to gain an advantage. Sosius in our story is fictional, for we know nothing about this freedman, nor does the summary of Dio hint at foul play behind the scenes of Longinus’ death. As stated at the start of the book, there was a Roman fort at a place called Piroboridava occupied at this time, but it was not located where it is in the story. Our Piroboridava is fictional, loosely based on the remnants of early phases of forts, such as the site at Rãcari in Romania. Counter attacks or large scale raids were a feature of Dacian war-making, partly for plunder and prestige, but also to wrong-foot the enemy. The heartland of Decebalus’ kingdom lay high in the mountains, which meant that it was virtually impossible to attack it on a large scale during the winter months. Thus delaying any Roman campaign was well worthwhile. When Hadrian became emperor, he had the Danube Bridge decommissioned, removing the road and leaving just the pillars and arches, which still looked impressive four centuries later. The Romans were not usually fond of bridges on their river frontiers, and some, like Hadrian, appear to have seen them as vulnerable spots. Trajan’s construction of the bridge was a sign of confidence, even bravado, which his successor did not share. Our story offers a reason for Hadrian’s fears and subsequent action.