The Sentinels video shows that Tiresia, the capital city of Tirol, has immense defenses, with previously hidden gun turrets appearing everywhere when the Invid attack, and they're old enough that the civilians don't remember their existance and are completely surprised when they start popping out. Until some time before Tirol, being the Robotech Masters' homeworld, had been protected by the Zentraedi fleets, whose warships totaled over five millions, closer to six, and the planet had been orbited by the Robotech Masters' motherships and their escorts. So what did the Masters' face in the past to fortify their capital city that way, and why did they feel the need to maintain the guns efficient?
It was likely just for show. The Masters could certainly spare the expense in building those guns, given that they were the wealthiest, most powerful civilization in the Milky Way within at least the past ten thousand years.
