Readiness

Readiness refers to how prepared a country's military is to fight an attack, either on offence or defence. When making attacks, readiness is multiplied directly with the attack strength; thus if a country's military is at 50% readiness, the attack will only be half as powerful. Defending has a minimum effective readiness of 70% however.

When sending 1/3 of your military forces you lose the minimum amount of readiness per attack. You lose 7% readiness per hit as a minimum And regain 3% per turn used.

Therefore: Tyr uses 1 turn to hit so it loses 4% Other gov types use 2 turns so its 1% While demo uses 3 turns so its 0%