だい日本 にっぽん帝国 ていこく陸軍 りくぐんだったら
dainipponteikokuri kugundattara

Noun
Da Copula

The "-tara" conditional form ("if/when…") of 大日本帝国陸軍

1. If it were the Imperial Japanese Army; If the Imperial Japanese Army were…

Tara Conditional