National Unity can be affected by the traits of [[country leaders]] or [[political advisors]], [[national spirits]], [[national focuses]], [[events]] etc. There also exist weekly National Unity modifiers.
When a country at war has lost a percentage of its [[Victory Points]] greater than its National Unity, it will capitulate (surrender). For example, if France loses more than 40% of its victory points, it will capitulate while Germany must lose over 90% of its victory points before capitulating.
Bear in mind, that even Non-VP-Provinces give a small amount of Victory Points. Surrender Progress can always be checked in the window of the corresponding war.