The Two Armies (二つの軍勢 Futatsu no Gunzei) is episode 2 of the Gate - Thus the JSDF Fought There! anime.
The army sent by the Empire to deal with the Japanese forces stationed at Alnus Hill where the Gate is located was obliterated by Japanese fire superiority. Emperor Molt calls for the vassal states to attack them, just to be defeated with huge casualties as well, a move planned in advance by the emperor to avoid the vassal states taking advantage of the Empire's weakened state. As Emperor Molt decides to delay a possible advance from the JSDF with scorched earth maneuvers, the President of the United States decides to leave the investigation of the Special Region to the JSDF for a while due to hopes that Japan will fail its venture into the special area allowing other countries to take control. Itami Youji is assigned to lead the 3rd Recon squad, created to survey the nearby cities and points of interest. After passing by the village of Coda, the 3rd Recon squad finds a massive Fire Dragon burning the nearby forest and then attacking and destroying a nearby settlement. While looking for survivors, Itami finds an unconscious elf woman inside a well by shear coincidence.
- The Second Battle of Alnus Hill is shown with all three charges done by the Imperial army rather than just the last night battle.
- Some of the lines exchanged between Itami and Kuribayashi were in a different order in the manga.
- Piña wore a toga when she met with the Emperor in the manga. In the anime, she wears her standard armor.
- In the manga, the Duke of League is shown to survive long enough to state the Battle of Alnus Hill is a completed slaughter while in the anime, he was killed instantly by the artillery.
- The first wave of the attacks manage to form the useless tortoise formation against artillery while in the anime, the first wave of attackers are killed instantly by artillery.
- In the anime, the JSDF puts the warning signs for trespasser in the Alnus Hill.
- When one of the soldier comes to report to king Duran, he is shown to ride the horse in the manga while in the anime he stands in front of the camp.
- The First Battle of Alnus Hill is depicted more detailed in the manga.