29A.53  Call by president of U.S.
  Whenever the United States is invaded or in danger of invasion from any foreign nation, or of rebellion against the authority of the government of the United States, or the president is unable, with the regular forces at the president’s command, to execute the laws of the union, it shall be lawful for the president to call forth such number of the national guard as the president may deem necessary to assist in repelling such invasion, suppressing such rebellion, or to assist in enabling the president to execute such laws, and to issue orders for that purpose, through the governor to such officers of the national guard as the president may think proper; and the president may specify, in the call, the period for which such service is required, and the guard so called forth shall continue to serve during the term so specified, either within or without the territory of the United States, unless sooner relieved by order of the president.
  Whenever the president shall require, in any of the designated instances, more troops than can be supplied by the national guard, the governor shall, in the governor’s discretion, organize forthwith such other national guard forces as the governor may deem necessary, or order into the service of the United States so many of the unorganized militia of the state as is required, designating the same by draft if a sufficient number do not volunteer, and shall commission officers therefor.
  Officers and enlisted personnel called into federal service through the national guard shall upon completion of such service continue to serve the balance of their enlistment period the same as though it had not been interrupted by such service.
[C97, §2169; S13, §2215-f18; C24, 27, 31, §448; C35, §467-f58; C39, §467.60; C46, 50, §29.60; C54, 58, 62, §29.53; C66, 71, 73, 75, 77, 79, 81, §29A.53]