Related Rule
Germany
Practice Relating to Rule 65. Perfidy
Section A. General
Germany’s Soldiers’ Manual (1991) defines perfidious acts as those “by which the adversary is induced to believe that there is a situation affording protection under public international law, so that he may be attacked by surprise”. 
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. 2.
Germany’s Military Manual (1992) provides: “Perfidy is prohibited. The term ‘perfidy’ refers to acts misleading the adverse party to believe that there is a situation affording protection under international law.” 
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, § 472; see also § 1018 (naval warfare).
Germany’s Soldiers’ Manual (2006) states that perfidious acts are those “by which the adversary is induced to believe that there is a situation affording protection under public international law, so that he may be attacked by surprise”. 
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. 2.
In 2010, in the Chechen Refugee case, Germany’s Federal Administrative Court was called upon to decide whether a Russian refugee claimant from Chechnya had to be excluded from refugee protection because there were serious reasons for considering that he had committed a war crime in Chechnya in 2002 by killing two Russian soldiers and taking a Russian officer hostage. The Court stated: “In some cases, unlawful perfidy and lawful ruses of war are difficult to distinguish”. 
Germany, Federal Administrative Court, Chechen Refugee case, Judgment, 16 February 2010, § 37.