From Hearts of Iron 3 Wiki
- Their military helps you in combat.
- Trade at discount and only with master.
- Free transit rights.
- Will supply your troops in their country.
- When attacking from puppet, you get the territory.
- When puppet conqers province, you get the territory.
- No partisans.
- Use a puppet country to block the land supply route. So you can continue to supply via Convoy.
- Use a puppet country to block the enemy. Puppet a country between you and the enemy.
- Resources, they send you any resources they have above 1000.
- A puppet has no foreign policy.
- Leadership points.
- Can not declare war on puppet.
- Can not transport resources through territory
- Can not transfer supplies through territory
- No Change in Ministers
- Can not deploy your army directly on their territory