So what does a fairy-tale king do when awaiting attack?
Calling up all the men in the kingdom is precluded because it's harvest time, and they've already discussed how the other king's kingdom is going to starve. Though he is gathering such forces as he can and even foreign knights are coming for the glory.
Points of defense, points of defense -- I think I can force the attackers onto one road, by making them too vulnerable strung out on the others. So the king will be setting up the most defensible point of it with greater defenses.
Most fairy tales use wars just to get the king away from the queen so that the fairy tale can go on, by false messages that result in the queen's exile, or the like. Occasionally the king gets captured, or the kingdom ravaged so the princess trapped in a tower emerges to find it basically gone, but those don't need tactics.