だい日本 にっぽん帝国 ていこく海軍 かいぐんだったら
dainipponteikokukaigundattara

Noun
Da Copula

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

1. If it had been the Imperial Japanese Navy; Had it been the Imperial Japanese Navy

Tara Conditional