In the speech, lewis and clark referred to a "great father" and "great chief. who was this? why do you think lewis used these terms?

Lewis and Clark referred to GOD as a "great father" and president/government as a "great chief"

Both speaker referred to GOD as a "great father" and president/government as a "great chief" in a sense that the great father is God and the great chief was the chief of the tribe.

They used the words in other toi sound boisterous and have the natives have a favorable view of him. "Great father" and "great chief" referred to the president and government of the United States.

In conclusion, Lewis and Clark referred to GOD as a "great father" and president/government as a "great chief"

Read more about Great father

link