First Lieutenant
Lieutenant
A military officer who's in the middle of their career has become a first lieutenant.
ちゅうい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
我が軍の中尉が敵軍に拉致され、処刑されました。
Our army’s first lieutenant was captured by the enemy and executed.