Eurotas > (Principal river of Sparta)
Cynthus > (A mountain on the island of Delos, the birthplace of
Apollo and Diana: these deities are thus also called Cynthius and
Cynthia respectively)

3 Where all the nymphs have her unwares forlorn,

unwares > unwittingly; unexpectedly forlorn > forsaken

4 Wanders alone with bow and arrows keen, 5 To seek her game: or as that famous queen

queen > (Penthesilea, an ally of Priam against the Greeks in the Trojan War; killed by Achilles or his son Pyrrhus)

6 Of Amazons, whom Pyrrhus did destroy,

Amazons > (A mythical race of warlike females, said to have come from the Caucasus and to have settled in Asia Minor, where they founded the city of Themiscyra. The Amazons were ruled by a queen, and the female children had their right breasts burned off so that they might better use a bow and arrow. The ninth labour of Hercules was to take the girdle of Hippolyte, an earlier queen of the Amazons)

7 The day that first of Priam she was seen,

of > by Priam > (The last king of Troy)

8 Did show herself in great triumphant joy, 9 To succour the weak state of sad afflicted Troy.