Related Rule
Germany
Practice Relating to Rule 103. Collective Punishments
Germany’s Soldiers’ Manual (1991) provides for the prohibition of collective punishment against civilians. 
Germany, Taschenkarte, Humanitäres Völkerrecht in bewaffneten Konflikten – Grundsätze, Bearbeitet nach ZDv 15/2, Humanitäres Völkerrecht in bewaffneten Konflikten – Handbuch, Zentrum Innere Führung, June 1991, p. 4.
Germany’s Military Manual (1992) refers to Article 33 of the 1949 Geneva Convention IV and prohibits “collective penalties” of civilians. 
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, § 507.
The manual specifies that this prohibition also applies in occupied territories. 
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, § 536.
With regard to prisoners of war, the manual refers to Article 87(3) of the 1949 Geneva Convention III and provides: “Collective punishment for individual acts and cruel punishment are forbidden.” 
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, § 725.
Germany’s IHL Manual (1996) states: “Collective punishments are prohibited.” 
Germany, ZDv 15/1, Humanitäres Völkerrecht in bewaffneten Konflikten – Grundsätze, DSK VV230120023, Bundesministerium der Verteidigung, June 1996, § 405.
Germany’s Soldiers’ Manual (2006) states: “Reprisals against the civilian population are prohibited, likewise taking of hostages, collective penalties, pillage as well as measures of intimidation or terrorization.” 
Germany, Druckschrift Einsatz Nr. 03, Humanitäres Völkerrecht in bewaffneten Konflikten Grundsätze, Erarbeitet nach ZDv 15/2, Humanitäres Völkerrecht in bewaffneten Konflikten Handbuch, DSK SF009320187, Bundesministerium der Verteidigung, R II 3, August 2006, p. 4.