No action or proceeding shall be prosecuted or maintained against a member of a military court, or officer or person acting under its authority or reviewing its proceedings, on account of the approval or imposition or execution of any sentence, or the imposition or collection of fine or penalty, or the execution of any warrant, writ, execution, process, or mandate of a military court, nor shall any member of the Virginia National Guard or Virginia Defense Force be liable to civil action or suit or criminal prosecution for any act done while in the discharge of his military duty. If any member of the Virginia National Guard or Virginia Defense Force is sued civilly or arrested, indicted, or otherwise prosecuted for any act committed in the discharge of his official duty while on state duty, the Adjutant General may employ special counsel approved by the Attorney General to defend such member. The compensation for special counsel employed pursuant to this section shall, subject to the approval by the Attorney General, be paid out of the funds appropriated for the administration of the Department of Military Affairs.