![](https://www.historynet.com/wp-content/uploads/2019/09/ACWP-191100-MERRILL-07.jpg)
A blockhouse along the Nashville & Chattanooga Railroad, one of more than 160 that Merrill would design. (Library of Congress)
A blockhouse along the Nashville & Chattanooga Railroad, one of more than 160 that Merrill would design. (Library of Congress)