Think about how difficult a land attack against Fort Adams would be. First, you would have to capture the Redoubt, located a quarter mile to the south. You would then have to charge up the sloping glacis to the Southern front. Finally, you would have to contend with cannon and musket fire from the exterior ditch, tenaille, exterior front and interior ditch. Remember that your own cannon fire is ineffective due to the materials and geometry of the fort's construction.
How about a tunneling attack? You could dig under the walls and blow them up to create a breech. The fort's builders, however, left nothing to chance. They constructed listening tunnels where soldiers could detect tunneling operations. When sounds of digging were heard, the defenders would dig their own tunnel in the direction of the sounds. When close, they would set charges and destroy the enemy tunnels.
[ Along Bottom of Marker : ]Redoubt - A small fort with its own defenses near a larger fort.
Glacis - A gentle slope of land away from the fort without any cover.
Exterior Front - Outer land defenses of the fort.
Ditch - A defensive trench that helps prevent attack and channelizes the enemy.
Tenaille - A wide angular defensive work used to protect the main walls.
Listening Tunnels - Tunnels designed so a soldier could hear the sounds of enemy digging.