A fortress would first be constructed and be free of the normal means of attack namely that the windows would be made out of bullet proof and shatter proof glass. Also there would be ventilation ducts too small for people to crawl through at all for any reason whatsoever.
To further make it hard to conquer him all soldiers would be given personally tailored uniforms so that no one could steal their uniforms and attack him disguised as one of his men. They would be given transparent helmets as well instead of face concealing ones.
The old military which consisted of Japae Sages would be given a choice namely surrender or die. Lord Montreal did want the Japae Sages in his army after all since he needed more forces. With a smirk he made the next phase of his plan which was to use the K-Archive to do research or rather have teams there researching what he wanted to know.
He turned on the cameras and sent a message to the general population of Japae from his magically constructed fortress that had been made from normal materials, but made with magic in it's construction.
http://media-cdn.tripadvisor.com/media/photo-s/01/14/e2/43/view-of-fortress-from.jpg His fortress was a massive 60 stories tall and had several gun turrets along with many other defenses including all anti fields except for AM (besides in the prison cells of course) active around it. Further he had drones patrolling instead of organic life forms.
“Attention people of Japae. I have taken complete control of your government and am now the sole ruler of Japae. Don't worry I won't change the way you are governed by much. But I do demand that your entire military surrenders or I will kill the former ruling party of Japae with my bare hands and my magical abilities. You have 2 hours to comply with this demand or their deaths will be brutal and vicious.â€
His fortress had been built over the K-Archive which he would use for his own purposes and was actually hidden in his fortress now so that no one could get into it besides himself or his soldiers.
All the spells on the land woven by other mages were taken apart by a brief use of AM fields. Once that had successfully been accomplished then Lord Montreal began phase two. Ordering his trusted generals to go out and seize every magical artifact in every museum, library and other place in Japae besides the K-Archive he planned to restrict the use of magic to the military that would now defend Japae.