Soul of the Navy is the squad story focused on Brian, Sergio, and André. The combat mission in this is called Naval Spirits. This squad story is only accessible in the postgame when they can be unlocked and enough CP is used on one of them.
This map is the same one used in the second part of Chapter 17: The Final Choice. Minor differences include no camps and different positions of cover and barricades.
Brian, Sergio, and André will start in the north part of the engine room, and must eliminate all Imperial troops before they reach the reactor as indicated on the map and by a sandbag perimeter.
This mission is an urgent one
"Imperial forces have made it into the Centurion's engine room. We believe they're targeting the reactor. Eliminate the enemy before they reach it. They've only sent infantry, so equip Dr. Mousquelaire with a mortar lance."
Location: Centurion, Engine Room
Description: Kick the infiltrators out of the engine room. Brian, André, and Sergio all share a duty to keep the enemy units away from their objective while staying alive.
"Let's begin the operation. Brian, Sergio, André... The whole crew is counting on you!"