A strong fortification was ordered and approved to be built here and Colonel Waul was placed in charge of the supervision of the construction. The walls were made of bales of cotton in zigzag fashion stacked four high and covered with dirt. The stacks were fourteen feet high and stretched from river to river. Cannon of various kinds were spaced evenly across the walls and guns were stationed to be used on approaching ships seen on either river. (From The von Rosenberg Family of Texas: The Civil War Years, by Ann Barnes) Read more here.