Grotius translates, “Because then (namely, on the third year) the time shall have come that,” etc.
confounded - at seeing their gods powerless to help them.
her slain - in retribution for “Israel’s slain” (Jer 51:49) who fell by her hand. Grotius translates, “her dancers,” as in Jdg 21:21, Jdg 21:23; 1Sa 18:6, the same Hebrew word is translated, alluding to the dancing revelry of the festival during which Cyrus took Babylon.