“army / military” in Japanese is 軍, read gun (ぐん). It is a Grade 4 Kyōiku kanji, taught in year 4 of Japanese elementary school, and appears in words such as 軍隊 (army / troops).
What does 軍 mean?
昔の軍の話を読む。
Same sound, different character — the classic trap. Compare them side by side: