From Pausanias,  2.20.8-10

“Beyond the theater is the shrine of Aphrodite. In front of the foundation is a stele on which Telesilla, a poet of lyric, is depicted. Her books are tossed near her feet while she looks at the helmet she holds in her hand as she is about to put it on her head. Telesilla was famous among women and especially honored for her poetry.

But a greater story about her comes from when the Argives were bested by Kleomenes the son of Alexandrides and the Lakedaimonians. Some Argives died during the battle itself and however many fled to the grove of Ares died there too—at first they left the grove under an armistice but they realized they were deceived and were burned with the rest in the grove. As a result, Kleomenes led the Spartans to an Argos bereft of men.

But Telesilla stationed on the wall of the city all the slaves who were unable to bear arms because of youth or old age and, after collecting however many weapons had been left in homes or in the shrines, she armed all the women at the strongest age and once she had armed herself they took up posts were the army was going to attack.

When the Spartans came near and the women were not awestruck by their battle-cry but waited and were fighting bravely, then the Spartans, because they reasoned that if they killed the women the victory would be ill-rumored even as their own defeat would come with great insult, yielded to the women.

The Pythian priestess had predicted this contest earlier in the prophecy relayed by Herodotus who may or may not have understood it (6.77):

But when the female conquers the male
And drives him away and wins glory for the Argives,
It will make many Argive women tear their cheeks.

These are the words of the oracle on the women’s accomplishment.”

ὑπὲρ δὲ τὸ θέατρον ᾿Αφροδίτης ἐστὶν ἱερόν, ἔμπροσθεν δὲ τοῦ ἕδους Τελέσιλλα ἡ ποιήσασα τὰ ᾄσματα ἐπείργασται στήλῃ· καὶ βιβλία μὲν ἐκεῖνα ἔρριπταί οἱ πρὸς τοῖς ποσίν, αὐτὴ δὲ ἐς κράνος ὁρᾷ κατέχουσα τῇ χειρὶ καὶ ἐπιτίθεσθαι τῇ κεφαλῇ μέλλουσα. ἦν δὲ ἡ Τελέσιλλα καὶ ἄλλως ἐν ταῖς γυναιξὶν εὐδόκιμος καὶ μᾶλλον ἐτιμᾶτο ἔτι ἐπὶ τῇ ποιήσει. συμβάντος δὲ ᾿Αργείοις ἀτυχῆσαι λόγου μειζόνως πρὸς Κλεομένην τὸν ᾿Αναξανδρίδου καὶ Λακεδαιμονίους, καὶ τῶν μὲν ἐν αὐτῇ πεπτωκότων τῇ μάχῃ, ὅσοι δὲ ἐς τὸ ἄλσος τοῦ ῎Αργου κατέφευγον διαφθαρέντων καὶ τούτων, τὰ μὲν πρῶτα ἐξιόντων κατὰ ὁμολογίαν, ὡς δὲ ἔγνωσαν ἀπατώμενοι συγκατακαυθέντων τῷ ἄλσει τῶν λοιπῶν, οὕτω τοὺς Λακεδαιμονίους Κλεομένης ἦγεν ἐπὶ ἔρημον ἀνδρῶν τὸ ῎Αργος. Τελέσιλλα δὲ οἰκέτας μὲν καὶ ὅσοι διὰ νεότητα ἢ γῆρας ὅπλα ἀδύνατοι φέρειν ἦσαν, τούτους μὲν πάντας ἀνεβίβασεν ἐπὶ τὸ τεῖχος, αὐτὴ δὲ ὁπόσα ἐν ταῖς οἰκίαις ὑπελείπετο καὶ τὰ ἐκ τῶν ἱερῶν ὅπλα ἀθροίσασα τὰς ἀκμαζούσας ἡλικίᾳ τῶν γυναικῶν ὥπλιζεν, ὁπλίσασα δὲ ἔτασσε κατὰ τοῦτο ᾗ τοὺς πολεμίους προσιόντας ἠπίστατο. ὡς δὲ <ἐγγὺς> ἐγίνοντο οἱ Λακεδαιμόνιοι καὶ αἱ γυναῖκες οὔτε τῷ ἀλαλαγμῷ  κατεπλάγησαν δεξάμεναί τε ἐμάχοντο ἐρρωμένως, ἐνταῦθα οἱ Λακεδαιμόνιοι, φρονήσαντες ὡς καὶ διαφθείρασί σφισι τὰς γυναῖκας ἐπιφθόνως τὸ κατόρθωμα ἕξει καὶ σφαλεῖσι μετὰ ὀνειδῶν γενήσοιτο ἡ συμφορά, ὑπείκουσι ταῖς γυναιξί. πρότερον δὲ ἔτι τὸν ἀγῶνα τοῦτον προεσήμηνεν ἡ Πυθία, καὶ τὸ λόγιον εἴτε ἄλλως εἴτε καὶ ὡς συνεὶς ἐδήλωσεν ῾Ηρόδοτος·

ἀλλ’ ὅταν ἡ θήλεια τὸν ἄρρενα νικήσασα
ἐξελάσῃ καὶ κῦδος ἐν ᾿Αργείοισιν ἄρηται,
πολλὰς ᾿Αργείων ἀμφιδρυφέας τότε θήσει.

τὰ μὲν ἐς τὸ ἔργον τῶν γυναικῶν ἔχοντα τοῦ χρησμοῦ ταῦτα ἦν·

Plutarch, On the Virtues of Women 245d-f6 reports a version of this tale; the Suda (s.v. Telesilla) likely takes its account from Pausanias.

“Telesilla, a poetess. On a stele her books are tossed around and she has placed a helmet on her head. And When the Lakedaimonians slaughtered the Argives who had fled to a shrine and were heading to the city to sack it, then Telesilla armed the women of the right age and set them against where they were marching. When the Lakedaimonians saw this, they turned back because they believed it shameful to fight against women whom it would be inglorious to conquer but a great reproached to be defeated by….” [the oracle is listed next”

Τελέσιλλα, ποιήτρια. ἐπὶ στήλης τὰ μὲν βιβλία ἀπέρριπτε, κράνος δὲ τῇ κεφαλῇ περιέθηκε. καὶ γὰρ ὅτε Λακεδαιμόνιοι τοὺς ἐν τῷ ἱερῷ τοῦ ῎Αργους καταφυγόντας διέφθειρον καὶ πρὸς τὴν πόλιν ᾔεσαν ὡς αἱρήσοντες, τότε Τελέσιλλα τὰς ἐν ἡλικίᾳ γυναῖκας ὁπλίσασα ὑπήντησεν οἷ προσῄεσαν. ὅπερ ἰδόντες οἱ Λακεδαιμόνιοι ἐς τοὐπίσω ὑπέστρεψαν, αἰσχρὸν νομίσαντες γυναιξὶ πολεμεῖν, ἃς καὶ τὸ νικᾶν ἄδοξον καὶ ἡττᾶσθαι μέγα ὄνειδος. ἐς τοῦτο καὶ ὁ χρησμὸς πεπλήρωτο, ᾿Αργείοις λέγων· ἀλλ’ ὅταν ἡ θήλεια τὸν ἄρρενα νικήσασα ἐξελάσῃ καὶ κῦδος ᾿Αργείοισιν ἄρηται, πολλὰς ᾿Αργείων ἀμφιδρυφέας τότε θήσει.

The extant fragments of Telesilla are not much to work with (each line is a separate fragment:

ἁ δ’ ῎Αρτεμις, ὦ κόραι,

φεύγοισα τὸν ᾿Αλφεόν

φιληλιάς,

†βελτιώτας

δῖνον.

οὐλοκίκιννε

〚ποιητριαν〛

〚Τελεσ̣ι̣λ̣λα̣ν̣〛