GATE - Jieitai Kanochi nite, Kaku Tatakaeri - Vol. 1 Ch. 8 - Alnus Hill

[MangaDex]

 

[GaryMahmud]

Page 24 literally sums the whole manga

 

[OllyMolly]

The old man is right. If this empire falls I hope the emperor does too. Let it be the greatest lesson to this backward world to not barge in too early to an alien world.

 

[humbleoverlord]

Basically, after the defeat of the Imperial Army, the emperor send the allied kingdom force to attack Alnus not only for revenge but also to reduce the other kingdom force to prevent rebellion.

 

[NekoHybrid]

Medieval Army: We outnumber them 300,000 to their measly 10,000! This will be no contest!

JSDF: Oh cool. They're all bunched up together.

 

[OHitsaComicAddict]

this world would've been fucked over in a mere month if they opened a gate at America