Related Rule
Germany
Practice Relating to Rule 27. Religious Personnel
Germany’s Military Manual (1992) states:
801. Chaplains are ministers of faith assigned to the armed forces of a state to provide spiritual care to the persons in their charge.
811. Chaplains shall be respected and protected in all circumstances. This shall apply:
–at any time throughout the duration of an armed conflict;
–at any place; and
–in any case in which chaplains are retained by the adversary, be it temporarily or for a prolonged period of time.
812. Chaplains as such are entitled to the protection provided by international law. Direct participation in rendering assistance to the victims of war (wounded, sick, shipwrecked, prisoners of war, protected civilians) is not required.
813. Unlike medical supplies, the articles used for religious purposes are not explicitly protected by international law. It is, however, in keeping with the tenor of the Geneva Conventions to respect the material required for religious purposes and not use it for alien ends.
816. Any attack directed against chaplains and any infringement of their rights constitutes a grave breach of international law, which shall be liable to criminal prosecution.
817. The fact that chaplains may be armed, and that they may use the arms in their own defence, or in that of the wounded, sick and shipwrecked shall not deprive them of the protection accorded to them by international law. They may use the arms only to repel attacks violating international law, but not to prevent capture.
818. The protection accorded to chaplains shall cease if they use their arms for any other purpose than that of self-protection and defending protected persons.
819. The only arms which may be used are weapons suited for self-defence and emergency aid (individual weapons).
820. In the Federal Republic of Germany chaplains are not armed. 
Germany, Humanitarian Law in Armed Conflicts – Manual, DSK VV207320067, edited by The Federal Ministry of Defence of the Federal Republic of Germany, VR II 3, August 1992, English translation of ZDv 15/2, Humanitäres Völkerrecht in bewaffneten Konflikten – Handbuch, August 1992, §§ 801, 811–813 and 816–820; see also § 315 (“chaplains are allowed to bear and use small arms”).