In Orberg's LLPSI Cap XXXVII he has:
Ecce virgo Cassandra crinibus passis a templo Minervae (ubi Aiax, Oilei, filius, ei vim attulerat).
Now I know there is no genitive or dative of vis (singular) and that vim is accusative. But what's vim doing in this sentence. It seems to mean (...where Aiax, son of Oileus, brought her violence - did violence to her)...assaulted her..,,