Captain
noun
The big military officer is in charge of everyone else. He's the captain. You can tell because he wears a really big captain hat.
たいい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
大尉の死は決して無駄ではなかった。
The captain’s death wasn’t useless by any means.