Related Rule
Germany
Practice Relating to Rule 22. The Principle of Precautions against the Effects of Attacks
Section A. Precautions to protect the civilian population, civilians and civilian objects
Germany’s Military Manual (1992) states: “Civil defence tasks are particularly warning … construction of shelters, and other measures to restore and maintain order.” 
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 KonfliktenHandbuch, August 1992, § 520.
The Report on the Practice of Germany states that the precautions required against the effects of attacks have to be taken mainly by the civil defence. It quotes a representative of the Ministry of Internal Affairs, who said at an ICRC expert meeting in Geneva that Germany had an integrated system of assistance to cover both peacetime disaster control and civil defence in case of armed conflict. 
Report on the Practice of Germany, 1997, Chapter 1.7.