軍鼓 is read as ぐんこ (gunko) and means war drum.
ぐんこ
gunko
ぐんたい
armed forces
ぐんこくしゅぎ
militarism
ぐんしゅく
reduction of armaments
ぐんかく
military expansion
ぐんかん
warship
ぐんじゅ
munitions
ぐんぞく
civilian in military employ
ぐんぴょう
military scrip
ぐんそう
sergeant
ぐんじきち
military base
ぐんきち
ぐんじせいさい
military sanction