Suda, s.v. Tyrtaios
“Tyrtaeus, a son of Arkhembrotos, Laconian or Milesian. An elegiac poet and an aulos player. The story goes that he used his songs to encourage the Spartans while they were fighting the Messenians and he made them stronger. He is really ancient, contemporaneous with the so-called Seven Sages, or even older. He peaked around the time of the 35th Olympiad. He wrote a Constitution for the Spartans and precepts in elegiac poems as a well as martial songs, 5 books worth.
Tyrtaeus: The Spartans swore to either seize Messenia or die trying. When Apollo prophesied that they should take a general from the Athenians, they took the poet Tyrtaeus, a disabled man. He helped them take Messenia by encouraging them to excellence. They razed the city and converted the warriors into Helots.”
Τυρταῖος, Ἀρχεμβρότου, Λάκων ἢ Μιλήσιος, ἐλεγειοποιὸς καὶ αὐλητής· ὃν λόγος τοῖς μέλεσι χρησάμενον παροτρῦναι Λακεδαιμονίους πολεμοῦντας Μεσσηνίοις καὶ ταύτῃ ἐπικρατεστέρους ποιῆσαι. ἔστι δὲ παλαίτατος, σύγχρονος τοῖς ἑπτὰ κληθεῖσι σοφοῖς, ἢ καὶ παλαίτερος. ἤκμαζε γοῦν κατὰ τὴν λέ ὀλυμπιάδα. ἔγραψε πολιτείαν Λακεδαιμονίοις, καὶ ὑποθήκας δι᾿ ἐλεγείας, καὶ μέλη πολεμιστήρια, βιβλία ε΄.
Τυρταῖος· ὅτι οἱ Λακεδαιμόνιοι ὤμοσαν ἢ Μεσσήνην αἱρήσειν ἢ αὐτοὶ τεθνήξεσθαι. χρήσαντος δὲ τοῦ θεοῦ στρατηγὸν παρὰ Ἀθηναίων λαβεῖν, λαμβάνουσι Τυρταῖον τὸν ποιητήν, χωλὸν ἄνδρα· ὃς ἐπ᾿ ἀρετὴν αὐτοὺς παρακαλῶν εἷλε τῷ κ΄ ἔτει τὴν Μεσσήνην. καὶ ταύτην κατέσκαψαν καὶ τοὺς αἰχμαλώτους ἐν τοῖς Εἵλωσι κατέταξαν.
Schol ad Plato Leges 1.629a-b
“That Tyrtaeus was Athenian, a humble person in his fortune. He was a teacher with a disability who was despised in Athens. Apollo prophesied to the Lakedaimonians to send for him–at that time when they were fighting the Messenians and were in great danger–because he would be just enough for them to figure out what would be advantageous. He ordered them to use him as an advisor.”
ὁ Τυρταῖος οὗτος Ἀθηναῖος ἐγένετο, εὐτελὴς τὴν τύχην· γραμματιστὴς γὰρ ἦν καὶ χωλὸς τὸ σῶμα, καταφρονούμενος ἐν Ἀθήναις. τοῦτον Λακεδαιμονίοις ἔχρησεν ὁ Ἀπόλλων μεταπέμψασθαι, ὅτε πρὸς Μεσσηνίους εἶχον τὴν μάχην καὶ ἐν ἀπορίᾳ κατέστησαν πολλῇ, ὡς δὴ ἱκανοῦ αὐτοῖς ἐσομένου πρὸς τὸ συνιδεῖν τὸ λυσιτελές· αὐτῷ γὰρ ἐπέτρεψε χρήσασθαι συμβούλῳ.
the biographical tradition that makes Tyrtaeus foreign to Laconia may be rooted in his poetic dialect. Tyrtaeus–unlike, say, Alcman–does not present a Doric dialect, but instead an Ionian dialect closer to the Panhellenic poetic forms favored by Homer and Hesiod. The stories attached to him can be seen, I think, as a individuated biographical allegory for Panhellenism.