222. The preposition εἰς (or ἐς) expresses motion to or intο. It is not used adverbially (the adverb being εἴσω), and seldom in tmesis.
Il. 8.115 τὼ δʼ εἰς ἀμφοτέρω Διομήδεος ἅρματα βήτην
The motion is sometimes implied.
Il. 15.275 ἐφάνη λῖς ἠϋγένειος εἰς ὁδόν
Il. 16.574 ἐς Πηλῆʼ ἱκέτευσε
(came as suppliant)
ἐς ἠέλιον καταδύντα
So ἐς τί how long? εἰς ὅ until.
Od. 14. 384 ἐς θέρος ἢ ἐς ὀπώρην
as late as summer or autumn
Il. 2.379 εἰ δέ ποτʼ ἔς γε μίαν βουλεύσομεν
if we take counsel to one purpose
Il. 9.102 εἰπεῖν εἰς ἀγαθόν
to speak to good effect
So Il. 11.789, 23.305.