The tone is of a narration and confessional.
Step-by-step explanation:
The tone used by Chief Joseph coveys his purpose with the speech. Joseph wanted to reach the white audience and tell them about the plight of the Natives by identifying with them.
He was trying to make them identify the people as their own by using a method of telling stories that they were familiar with.
So he employs a tone that is confessional and narrates a story directly to the audience to make them identify with the native subject more easily.