One month and this is all I get? I've forgotten how agonizingly slow adaptations of Japanese LNs are. Korean manhua have spoiled me. I'd take biweekly releases over basically forgetting the entire plot every chapter.
They've defeated the barbed wire, I'll give them that. Excellent job, pats on the back all around. They have attained the privilege to "solid ground" until the first trench, and it seems they are being given the privilege to stand upright for free. What an amazing luxury they are being given, it'd be a shame if something happened to it, or any of the other luxuries they are unaware they are being given.
... All they did was make 1 (big) hole in the primary defenses. Effectively funneling the army in 1 concentrated point. They'll be like fish in a barrel for artillery & archers while a final blow from some kind of AoE (like a river) can mop 'm up in 1 fell swoop. Victory? Yes, but not for them haha!
they will be hit with flaming oil that they won't be able to deal with for a while, then comes the flooding with the dam and after that the reason they didn't use too many mages will be revealed, they were heating lumps of iron that was then launched into the remains of said flooding and causing steam explosions left and right and afterwards in the confusion they eliminated most of the the chain of command so comes the retreat but I might be forgetting some parts
With the monthly release and this pacing it will take far too long for this story so I recommend you read the ln