Turnus Herdōnius ab Arīciā ferōciter in absentem Tarquinium erat invectus.
I have a syntax question here. Why is erat placed before invectus instead of after it as is usually the case?
As you undoubtedly know, Latin word order is very flexible, and it’s more or less independent of syntax. The past participle is the element of the periphrastic pluperfect form that carries the idea of the verb. Placing the past participle at the end of the sentence perhaps puts a slight emphasis on the verbal idea.