Complex sentence: In 88 AD, the Emperor Domitian ordered the Legio II "Adiutrix" to the lower Danube; the Legio XX "Valeria Victrix" became the new garrison at Deva Victrix after abandoning the fort they were building in Scotland at Inchtuthil.
Split into simpler sentences: In 88 AD, the Emperor Domitian ordered the Legio II "Adiutrix" to the lower Danube. The Legio XX "Valeria Victrix" was deployed to garrison Deva Victrix, abandoning the fort they had been building in Scotland, at Inchtuthil.