White Peace is a peace treaty that a president can declare 24 hours after war started. When white peace created, then countries can't attack anymore together.
Example:
Russia attacks USA. USA loses many regions. Then the president of USA declare white peace with president of Russia. President of Russia must to decide: To ignore white peace and continue war or declare white peace. And Russian president will declare it. That means, Russia can't anymore attack USA or USA can't attack Russia. If president of Russia declares war to USA he/she has two decisions: To destroy white peace and attack or just nothing. Countries that made war and one side winned many regions, then white peace recreate original borders between those two countries. It will make automatic alliance, too. And that alliance lasts forever. No trading embargos between our example countries or other countries that have White Peace.