Obverse
賞 - award
reverse
海軍兵学校 - Naval Academy
In the center
勝て兜の緒を締めよ = 勝って兜の緒を締めよう
"After victory, tighten your helmet cords" i.e. even after a victory, prepare for the next battle and do not let your guard down.
At the bottom
通信 - signaling/communication
Case.