Having served during World War II as Marine Corps liaison officer to the Selective Service Headquarters in Iowa and Nebraska and later as Training Officer attached to the National Headquarters where he assisted in the preparation of correspondence courses and training materials for the instruction of Reservists earmarked for mobilization assignment to Selective Service, Major Rankin is now Chief of the Manpower Section of the Iowa State Headquarters of Selective Service. He is also the author of several military affairs articles published in the The National Guardsman and other magazines.