As the last great Dwarven realm in the West, Erebor serves as the capital of the few surviving Longbeards. Founded in T.A. 1999 after the fall of Khazad-dum, the Lonely Mountain has produced many riches, and from here many other colonies established. Sadly, the Kingdom under the Mountain had suffered from a Dragon-infestation from T.A. 2770-2941, though it has since been restored to its former glory, and once again stands as the greatest surviving kingdom of Durin's Folk. The closest edge of the Iron Hills, Erebor's sub-HQ, lies about fifty miles to the east (just on the other side of Celduin).
As it's common name would imply, the Lonely Mountain is the only peak for many miles (possibly being a long-extinct volcano), and is surrounded by flatlands. The mountain itself is star-shaped, with six arms protruding outwards. A guard-tower known as Ravenhill rests on the southwestern arm, overlooking the way to the Front Gate which lies in between the two southern arms. It is here, inside Erebor, that the River Running originates, coming up from the depths of the Mountain and flowing out the Front Gate over a waterfall, which leads into the valley below. Just inside the gate, a broad road (whose walls are ornately carved, but is otherwise fairly plain) follows the river a ways in, eventually opening up into the Great Chamber of Thror. While the river may simply come up through a hole in the wall somewhere overhead, a masterwork of aqueducts channel the water into an array of waterfalls before guiding it all back into a single stream to run out the gate, framing an already exquisite hall. A network of stone bridges overlooks the floor and lead into the rest of the kingdom, while numerous balconies offer great vantage points for the entire room. Just before reaching this grand chamber, the main road splits into three separate paths: one leading into a grand gate which opens onto the floor of the Great Chamber of Thror, while two smaller paths lead upwards to the sides, and open onto one of the lower bridges. A hidden tunnel also leads from the front hall to "The Bottommost Cellar", which in turn has a tunnel leading to the Back Door on Erebor's western face. (Note: I obviously took some creative liberty as to the details of the Mountain's entrance, but all known canonical details have been included, with no extreme additions.)
Erebor's military primarily consists of heavy infantry, but also uses a wide variety of advanced siege weaponry, including tank-like vehicles. While it has no cavalry force of its own, its sub-HQ, the Iron Hills, uses boars to fill this gap. And due to the relatively low Dwarven population and the known strength of even small Dwarven contingents, Erebor has a troop limit of fifteen thousand troops, equal to the standard twenty thousand MWE (one and a third MWE per troop).
Three locations border the Lonely Mountain: Mirkwood to the west, Dale to the south, and Celduin to the east. The Withered Heath lies just north of Erebor, but it is separated by an arm of the Grey Mountains.
*Almost the entire Host Under the Mountain gears up and moves out the Front Gate. As if a mere few hundred Dwarves weren't dreaded enough, an army numbering fifteen thousand troops marches out in formation, bearing hundreds of artillery pieces with them.*
Oh, and while I'm still working on day #1 moves. . . *The troops remaining here work on extra defenses. Work continues until otherwise specified (it'll take a while ).*