The American Battlefield Protection Program has one of the best summaries of the Battle of Fort Sanders:
“In attempting to take Knoxville, the Confederates decided that Fort Sanders was the only vulnerable place where they could penetrate Union Maj. Gen. Ambrose E. Burnside’s fortifications, which enclosed the city, and successfully conclude the siege, already a week long…”
Read the rest here. It is an odd association, however, as in Knoxville there is no battlefield to preserve. It disappeared under developed real estate long ago.