attack-signaling drum
Historical term for a drum used in ancient Japanese warfare to signal the start of an attack.
In battles of the Warring States period, soldiers charged as soon as the attack drum was sounded.
Compound of 攻め (seme, 'attack', the continuative form of 攻める) and 太鼓 (taiko, 'drum'). The exact historical origin is uncertain, but the term refers to a specific military signaling instrument.