Hmm... lets see... To answer your question Aristo:
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.
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.