What part did I miss? The only point I didn't directly address is that part about baiting them into a mundane attack, which is covered by the last line. Ice/Water themed magical attacks are better resisted from stone fortifications than a wooden palisade.
And most of the smaller monsters have very little that works on that big stone wall.
"therefore they knew it was going to be a powered up version of a lizard. So it is likely to have animalistic monsters under its command which might not have the patience to siege their town, unlike an army of goblins. An ice-using commander unit is much better resisted from the walls rather than a wooden barricade."
1) Winter Lords vary, as do their minions. They knew the Winter Lord was a lesser dragon, because they had fought it and failed to kill it in a previous year. They aren't always lesser dragons.
2) I said that they have magical ice/cold usable by
at least the upper echelons; we have no idea if the lower troops do as well. The entire concern of our MC is the town (really, just the orphanage and those she cares about) getting frozen through, which if they just played defense without combating them, would happen.
3) an ice-using commander is not better resisted from the stone wall. The only thing the stone wall affords you is the enemy melee being unable to reach you in a non-magical world, and superior archery positioning. It doesn't grant any form of resistance, nor does it enable you to hide behind it to avoid a localized magical blizzard or polar vortex or similar. Engaging with the enemy prevents that.
So no, you didn't directly address anything I said, just went "I agree" and then went off on your own tangent that didn't agree with what I said at all.
If the army disperses, that's already a successful defence of the town. And it absolutely is their speciality if the army scatters. That's more or less what adventurers are for and there's a big excess of them in town at the moment. When the anti-Winter Lord team gets back, they can start a big sweep of the scattered monsters while the high level prince faces down their commander.
Just like driving off the Winter Lord, huh? Except it's not. It just comes back meaner and stronger than before. Same would go for its minions. They want to eradicate the danger, not make the entire countryside dangerous from another threat.
No, adventurers are not specialized in dealing with an army of monsters, even if spread out. They're good at dealing with small pockets of monsters to keep their levels and numbers from getting out of hand, which is already too late in this situation.
Even when the anti-Winter Lord team returns, they can't put on a massive sweep; they can put on a tiny one, that could temporarily clear one area, but there'd still be a plethora of enemies left behind, even if they stayed for a very long time and scoured the countryside. Pincering the enemy between the town's forces and the AWL team is their best bet for continued survival.
If the monster army retreats in good order and diverts to somewhere else, that's added travel time for the anti-Winter Lord team to catch up and whack it. Time in which those monsters aren't doing very much besides walking around the countryside.
Except no, it's not, unless they divert back towards the Winter Lord and thus drastically reduce the distance travelled; considering the makeup of the WL army, they can outpace humans easily. You really underestimate what a threat they are facing functionally; the artist's bad use of static shots isn't helping, that's for sure.
Fundamentally, the monsters are a superior force to the town's adventurers (minus MC) but are weaker than the anti-Winter Lord team. So the town's defenders' objectives should be to hold out and save their manpower for when everyone can get together and decisively crush the monsters, not to fight them.
Vector himself is basically the one carrying them on that foot; remember that the AWL team basically had no chance of success without the MC's gear boosting him. The rest are there more as support and to deal with minions that remain at the WL's side, not because they are superior to the entire army that was fielded by the WL.
With that said, the town's defenders' objective IS to hold out and save their manpower to hold the WL army for long enough that they can be decisively crushed. How you can understand THAT but not that they need to engage them to do so baffles me.
All of these points only have better results from defending the stone wall compared to the barricades. Furthermore, the bit at the start of chapter 73 shows they were about to get overrun. Which would not have happened if they were defending the wall. Heck, even defending inside the gatehouse is still better than in front of it to restrict the frontage and thus the number of people fighting at once, plus added stuff like murderholes in the roof adding more firepower.
The guard captain outright states that they were in danger of getting overrun and were going to retreat if it weren't for the MC showing up. They sallied forth, fought as long as they could reasonably do so without drastically reducing manpower, as they fought only to light casualties, then were going to retreat.
Fighting solely in cramped quarters within the gatehouse would have been a terrible idea because it doesn't allow for any fallback locations, allows the wolves to do their best work as harrying units, and puts them further in a disadvantageous situation because the monster army can cycle troops easily, due to their superior manpower; the defenders would be exhausted long before they were able to do as much damage as they have already, not counting the MC.
The monsters do not have siege, they are incredibly ineffective against a stone wall. At least not until the giant shows up, but the giant is impossible for the adventurers without MC anyway.
"The monsters do not have siege" what do you think magic is? The giant showing up is far, far, FAR beyond siege; he is a wallbreaker, able to deal massive damage with even just a single shot, while traditional siege would take hours, if not days or even weeks to take down those walls. And that, again, is if they didn't just surround the town and freeze it out, instead.
