It was the eastern section of the so-called Danubian Limes[1] and protected the Roman provinces of Upper and Lower Moesia south of the river.
Legion IV Scythica was initially stationed in Moesia (probably at Viminacium) to counter threats from neighbouring Thrace and aggressive peoples north of the Danube.
But as a result of the Dacians constant looting that occurred whenever the Danube froze, Augustus decided to send against them some of his proven generals such as Sextus Aelius Catus and Gnaeus Cornelius Lentulus Augur (sometime between 1-11 AD[10]).
In the winter of 98/99 AD Trajan arrived on the Danube, quartered at the Diana Fort near Kladovo,[citation needed] and started Dacian war preparations on the Iron Gates gorges.
In 101 he also cut a canal nearby, as he also recorded on a marble plaque near Diana Fort which reads: “because of the dangerous cataracts he diverted the river and made the whole Danube navigable”: (ob periculum cataractarum, derivato flumine, tutam Danuvii navigationem facit).Trajan restored stone defences in the area and rebuilt all earthworks in stone.
[citation needed] Between the first and second Dacian wars, from 103 to 105, the imperial architect Apollodorus of Damascus constructed Trajan's Bridge, one of the greatest achievements in Roman architecture.
[16] In the Late Roman period, the extent of control and military occupation over territory north of the Danube remains controversial.
[20] Similarly, although considered 1st century and believed to predate the Limes Transalutanus, the function and origins of a shorter section of bank and ditch known as the "Brazda lui Novac de Sud" remain uncertain.