In the latter two cases, soldiers and officers are isolated from society and can represent a praetorian challenge to legitimate rule.
Titus and Domitian were not close (they were separated in age by 21 years) and so while Titus was dying, Domitian left for the praetorian camp where he was hailed as emperor.
The head of the civil administration as far as Britain was concerned was the praetorian prefect of the Gauls, based in Trier, to whom the vicarius of the British diocese was responsible.
A herdsman, tough and uneducated, he rose high in the army and became praetorian prefect of Diocletian, to whom his loyalty was unswerving.
Eventually the Visigoths, after a brief period of fighting for the Romans in Spain, were established in south-west Gaul in 418 by the praetorian prefect.
There actually is quite the rounded out selection of units to make as well, ranging from infantry to spearman to archers to legionnaires to praetorians and beyond.
Though you are one century short from a cohort, you will be known as the storm cohort, as elite as the praetorians in status.
Although Vindex was defeated, Nero's suicide and the support of Gaius Nymphidius Sabinus and the praetorians encouraged Galba to march on Rome, accompanied by Otho, governor of Lusitania.