It has been reported to be bugged (glitched) and no longer works as of an earlier update in the game. The white peace command can be used to instantly create white peace between two countries.

If not, see our opening the console guide and country tags help. This guide assumes that you know how to open and use the console, and know what country tags are. The same goes for money and cores (nothing is exchanged, things go back to the way they were before the war). Things returning to the way they were before war means territory goes back to the way it was before the war started (so any territory gained during the war from an opposition is returned).

When white peace is made between two countries at war, the war and all forms of hostilities stop and things return to the way they were prior to the war. White peace is a peace treaty for countries at war.