"Well, cadets, the topic for today's discussion is defensive fortifications, namely the Hegemony's Castles Brian. First, who can tell me how many there are? Cadet Jackson?"
"As of last year, there were more than 120 Castle Brians. The six on the world of Lambrecht represent the most on any single planet."
"Very good, Cadet Jackson. Now, who can tell me the average firepower and unit strength of a Castle Brian. Cadet Ivey?"
"Each Castle Brian has a minimum of 20 heavily armed turrets carrying an assortment of weapons and missiles. In addition to these active fortifications is the passive strength of the fortress itself, which is usually built deep inside a mountain and is virtually impregnable to anything but a full-scale nuclear blast."
"Excellent. Now for the big question. What is the purpose of a Castle Brian? Cadet Green?"
"To prevent the invasion and takeover of a Hegemony planet?"
"Absolutely incorrect. It has always been a failing of strategists to believe that a fortress protects and prevents the surrounding land from being taken over by an enemy. A fortress could only do that if it was built completely around the countryside it was to protect. Just look at what a mess the Maginot Line caused the French. They thought that building a huge network of fortresses would keep the Germans out. Trouble was, they were so confident of their Line that they didn't even bother to see it finished to the Atlantic coast. When the Germans wanted to invade France, all they had to do was run around the northern end of the Maginot Line into France. The French were so sure of their fortifications that they hadn't even bothered to design Maginot Line turrets to swivel around and fire into France. No, Castles Brian aren't meant to protect anything but themselves.
"Cadet Guilliam?"
"A Castle Brian is meant to be a permanent hindrance against an enemy taking the planet."
"Can you expand on that thought?"
"Castles Brian, with their stockpile of weapons, food, and men, represent a permanent threat to any enemy attempting to seize control of the planet. Because more than one Castle Brian is on most border worlds, they represent a major hidden force than can attack the enemy almost at will. If an enemy really wanted to take a Hegemony world protected by Castles Brian, it would have to do so with a huge force of men and equipment and would have to remain on that planet for a very long time. It is a price most enemies are not willing to pay."
"Excellent, Cadet Guilliam. It's good to see that someone studied the material."