The act of one who voluntarily enters the military or naval service of the government, contracting to serve In a subordinate capacity. Morrissey v. Perry, 137 U. S. 157, 11 Sup. Ct. 57, 34 L. Ed. 644; Babbitt v. U. S., 16 Ct. Cl. 213; Erichsou v. Beach, 40 Conn. 28G