When you leave the alliance, your contributions and your medals (including the ones in your backpack) will disappear, and you will get a warning message before leaving the alliance. Are you sure you want to leave the alliance? You will lose Medals and alliance honor when you leave the alliance.

Note: If you return to the same alliance without joining another one during the period you left, your contributions and medals you donated to the alliance will be reverted. However, the medals that were in your backpack and you did not use before you left the alliance will not return.