ἐτάττοντο means "they were lining up (for battle)" or "they were being posted (as guards)".
καίτοι means "however".
It's interesting that you translated "ἐχθρός" as "hated one", because ἔχθος "hate" is where the word comes from, but in Attic Greek you'll find that it means simply "enemy".
"The hoplites were lining up in this here* plain beyond the road. However, the others were being sent out of this land to these islands where every man was being wronged/harmed by the/our enemies"
*As nit-picky as this is, I translated τῷδε as "here". It's as if he's showing, explaining which one he means.