Now chronology becomes a little hazy, so I may be somewhat off, but my assumption is that Septimius Severus attempted to take Hatra again early this year, when the weather in this part of the world is still mild. The emperor brought with him large stores of food and plenty of siege engines. The inhabitants of Hatra were prepared as well. They even resorted to some sort of chemical warfare. Dio claims they threw pots containing bituminous naphtha at the attacking Romans, which consumed both men and machines. Herodianus writes that they also hurled at the Romans “clay pots (…) filled (…) with winged insects, little poisonous flying creatures”. Foraging expeditions were constantly harassed by swift Arabian horsemen and the Romans lost many men there as well. The Romans did manage to break down part of the walls of Hatra, but they failed to capitalise on their success. After twenty days, the emperor decided to pull back to Palestine.
Touring the Empire
The emperor would spend the rest of the year in Palestine and Egypt. In Alexandria, he gave the ius buleutarum (the right to have a βουλή) to the Alexandrines, something that Caesar Augustus had refused them decades ago. The city had been administered by a single administrator, the iuridicus Alexandriae, but was now granted the right to have a council. It is interesting that the Historia Augusta claims that Severus, while confirming a great number of privileges for the Palestinians, also “forbade conversion to Judaism under heavy penalties and enacted a similar law in regard to the Christians”. Jewish revolts and rebellions had of course already caused some of his predecessors – Vespasian in 66-73, Trajan in 115-117, Hadrian in 132-135 – a lot of trouble. Possibly Severus expected similar trouble from the Christians, who by now had become a religious group clearly distinct from the Jews.
– Adrian Goldsworthy, The Fall of the West, p. 67-68.