[quote=Ellri]
A. Invasion wasn't expected.
B. One normally has no need to heavily defend a mountain range that is considered impassable.
C. The borders needing defense are elsewhere. That would mean that the best troops would be at those places, not in the capital.
D. There's probably been peace for quite a while, so most peaceful nations would not have a large standing army.
E. They were having a coronation celebration. Most are distracted by that.
F. We'd fully expect the King to have some proper guards with him. Guards with decent training. Those won't be easily defeated.
G. They had a big massive distraction to hide the Army's approach.

Need we go on?

Mind you, if they're too effective later on, when the defenders get a bit more collected, this'll mean Trouble for Thora. She's got absolutely no interest in "re-education" or service to an empress she doesn't know.
[/quote]

These are all true, when they reach the inner wall it will be a more difficult fight.

B. We only have two actually fortresses in the mountains, one is to the east in the largest of the passes (which is incredibly difficult terrain already.) The second is in the south, where Lendrians and Ceranians often travel through.

C. Yes, that would be a small contingent to the south and a sizeable force along the Oragos border to the west where border disputes are common. (Which is why Da-Hyun was seeking Othean aid in a war against Oragos.)

And a note, Amaryth used to be a fortress several hundred years ago. It grew into the capital of Othea, which is why the inner city (and the harbor) are more tactically designed than the sprawling outer sections.