Age of Empires IV: Anniversary Edition

You'll need to get the upgrade in Castle Age for archers called poison arrow. Once you've got that your archers will inflict bleed over time damage onto their targets. This is the key to unlocking the achievement. DivineShai and I have discovered that it truly needs to be a heavy cavalry unit. The Malians cav will not work. Something like a knight works perfectly for this (aka the French).

The achievement is a bit slow to pop so give it a bit. May be best to try and farm a few knights before waiting.