Who often supplied Union troops information on navigating through the unfamiliar terrain of the south?

It might be said that African American scouts supplied Union troops information on navigating through the unfamiliar terrain of the South. The Union military plan was to defeat the South dividing the Conference in two. On the other hand, the south had a very strong military defence.

Some of the people who believed in the union plan but live in the south so that showed the union through the south