Whenever the Kansas national guard, or any portion thereof, shall have been called or drafted into the service of the United States as provided by federal law, all persons so called or drafted shall, upon their discharge, muster out or release from the service of the United States, resume their membership in the Kansas national guard and shall continue to serve therein until the dates upon which their commissions or enlistments entered into prior to their call or draft would have expired if uninterrupted.