The latter included Holland and the Rhineland south to Cologne. This once lovely city, known to the Romans as Colonia Agrippinensis, had been made a colony (A.D. 50) in honor of Nero’s mother, who had been born there; half a century later it was the most opulent settlement on the Rhine. The province of Upper Germany followed the Rhine southward through Moguntiacum (Mayence), Aquae Aureliae (Baden-Baden), Argentoratum (Strasbourg), and Augusta Rauricorum (Augst) to Vindonissa (Windisch). Nearly all these towns had the usual array of temples, basilicas, theaters, baths, and public statuary.
Many of the legionaries sent by Rome to guard the Rhine lived outside their camps, married German girls, and remained as citizens when their term of service was complete. The Rhineland was probably as thickly settled and affluent in Roman days as at any time before the nineteenth century. Between the Rhine and the Danube, as we have seen, Rome’s military engineers built a fortified road (limes), with a fortress every nine miles, and 300 miles of wall. It served Rome for a century, but availed little when the Roman birth rate fell too far below the German. Still weaker as a frontier was the Danube, which the ancients considered the longest river in the world.
South of it lay the half-barbarous provinces of Raetia, Noricum, and Pannonia, approximately composing what our youth knew as Austria-Hungary and Serbia. On the site of modern Augsburg (i.e., Augustus’ town) the Romans established a colony, Augusta Vindelicorum, as a main station on the road from Italy over the Brenner Pass to the Danube. On the river they built two fortress cities- at Vindobona, now Vienna, and at Aquincum on the heights from which Buda looks down upon Pesth.
In southeastern Pannonia, on the Save River west of the modern Belgrade, the city of Sirmium (Mitrovica) rose to be in Diocletian’s time one of the four imperial capitals. South of Pannonia, in the province of Dalmatia, the commercial energy of Greeks, Romans, and natives had developed the Adriatic ports of Salona (Spalato), Apollonia (near Valona), and Dyrrhachium (Durazzo).
From these provinces below the Danube came imperial Rome’s sturdiest soldiers and, in the third century, the martial emperors who would for 200 years hold back the barbarian avalanche. East of Pannonia lay Dacia (Rumania), with its now vanished capital of Sarmizegetusa. South and east of this Moesia (parts of Yugoslavia, Rumania, and Bulgaria) boasted two cities on the Danube- Singidunum (Belgrade) and Troesmis (Iglitza); one near the Isker- Sardica (Sofia); and three major towns on the Black Sea- Istrus, Tomi (Constanta), and Odessus (Varna). In these harassed settlements Greek civilization and Roman arms struggled in vain to maintain themselves against the Goths, Sarmatians, Huns, and other barbarian tribes breeding and wandering north of the great stream.
It was Rome’s inability to civilize these provinces south of the Danube that led to her fall. The task was too great for a people suffering from old age; the vitality of the master race was ebbing in sterile comfort while the tribes of the north were advancing in reckless health. When Trajan subsidized the Sarmatians to keep the peace it was the beginning of the end; when Marcus Aurelius brought thousands of Germans into the Empire as settlers, the dikes were down. German soldiers were welcomed into the Roman army and rose to positions of command; German families multiplied in Italy while Italian families died. In this process the movement of Romanization was reversed: the barbarians were barbarizing Rome.