The 818th Medical Brigade was first constituted and activated in Belgium as the 818th Medical Service Detachment in the fall of 1944 (activated 22 November 1944). Before the end of World War, the unit took part in the Rhineland campaign and was reorganized and redesignated on 10 April 1945 as the 818th Hospital Center.
It was allotted to the Army Reserve and assigned to First Army while being redesignated as Headquarters, 818th Hospital Center. Over the next forty years, the unit would undergo two minor redesignations—once as the 818th Medial Detachment and another as the 818th Hospital Center (again), a designation it carried while serving in two Gulf War campaigns—before receiving its current designation as the Headquarters and Headquarters Company, 818th Medical Brigade on 17 September 1992.
Originally approved while the unit was designated the 818th Hospital Center on 12 October 1990, the 818th Medical Brigade Shoulder Sleeve Insignia, or unit patch, was redesignated with revised symbolism on the same day unit became a brigade (17 September 1992). It features a winged staff superimposed on a maroon cross in the center of a white disc with golden border. The golden symbolizes the total comprehensive support provided by the Brigade and its continuity of service, while the staff represents the medical mission of the unit.