Is there a time when the god Artemis showed great leadership?

Artemis is a goddess ... so are you asking the right question (ie is the God correct??)

She shows leadership right after her birth -- she immediately assists her mother, Leto in birthing her twin brother, Apollo.

She leads her nymphs on hunts throughout Greece that she so enjoys. She kills any number of men who attempt to take advantage of her sexually. She sided with the Trojans during the famous war ....

Also there is the myth where she sets up the death of two giants who were called the Aloadai. ....Otos and Ephialtes, who were known as Aloadai. .... they decided to fight the gods. So they set Mount Ossa on top of Mount Olympos, and then placed Mount Pelion on top of Ossa, threatening by means of these mountains to climb up to the sky ... Ephialtes paid amorous attention to Hera, as did Otos to Artemis … Artemis finished off the Aloadai in Naxos by means of a trick: in the likeness of a deer she darted between them, and in their desire to hit the animal they speared each other."

Pretty smart trick by the Goddess.....