Why were fortifications necessary? What was the purpose of the earthen fortifications at Forts Henry, Heiman, and Donelson? Objective Three objectives: 1. To help students understand Civil War fortifications at Fort Donelson (polygonal shapes, locations on maps, Civil War terminology) 2. To help students understand why rivers were important during the Civil War, and why forts were needed 3. To encourage thoughts and reflection on historic preservation and resource protection Background When the Civil War began, Tennesseeans did not immediately cast their votes for secession. It would not be un Duration: 60 Minutes.