I’m very keen on stopping fighting…especially by psychological means.
Today’s invention is a bullet design which is fired in a short burst at the walls of an enemy fortification. Each round contains a chip with sounds recorded on it, a small speaker, a battery and a light-sensitive switch.

At night, these bullets begin to emit an intermittent chirping sound which can’t be stopped because they are embedded in wood, masonry etc. Sleep would become difficult and nerves strained. The bullets would be hard to locate or muffle -both because of the frequencies employed and because they are within sight, and range, of the opposition.
The rounds might even squeak certain words and phrases like ‘retreat’, ‘fear’, ‘I’m scared’ -whatever it takes to encourage a peaceful withdrawal. In addition, some of them might contain a secondary charge, timed to go *bang*, right next to where personnel are sheltering.
The recorded voices would obviously have to speak in the language of the army to whom they are directed. An elaboration on this scheme would mirror the actions of soldiers writing “Take that, Adolf” on shell casings. It would involve allowing soldiers to record their own messages in the bullets and thus help to downgrade the conflict to an exchange of verbal abuse.