Sacred Days, Silent Guns?

The relationship between religion and international humanitarian law (IHL) has been the subject of academic study for decades: Rules of IHL are reflected in the teachings of most if not all religions and IHL requires the parties to the conflict to respect the adversary’s religion at least to some extent (see, e.g., here). Similarly, it is a commonplace that religion can be a driver of armed conflict (see, e.g., here, pp. 14ff.). A nexus that has received less attention, however, is that of religion, armed conflict, and time: When observing current armed conflicts, it is conspicuous that many such conflicts were initiated or continued on religious holidays. When Hamas and other armed groups attacked Israel on 7 October 2023, e.g., several commentators noted that the attack was carried out on Simchat Torah, a major Jewish holiday (see here, here, and here). Similarly, when Israel decided to block the provision of aid into Gaza in March 2025, this decision was not only criticized for its merit but also its timing: just at the beginning of the holy month of Ramadan (see here, here, and here).

This post examines the relationship between religion, armed conflict, and time. It first establishes the correlation between religious holidays and military attacks, examines possible motives for attacking enemies on their religious holidays and identifies these attacks as morally objectionable. It then analyses whether there exists a corresponding legal obligation under IHL that explicitly or implicitly prohibits attacking enemy forces on a religious holiday celebrated by a significant part of the adversary’s population.

Attacks on Holidays

Besides the two examples named above, readers will be quick to recall further examples of attacks that either were initiated or continued on religious holidays observed (also) by the adversary. The 1973 Arab-Israeli war, for instance, is widely known as the “Yom Kippur War” by reference to the Jewish religious holiday that was celebrated on 6 October 1973, when Egypt and Syria launched their first attack; notably, Yom Kippur coincided with the tenth day of Ramadan and was thus a religious holiday for all parties. Similarly, during the first Gulf war, the Iranian “Operation Ramadan” was started on the first day of Ramadan and in the Vietnam war, the Viet Cong and the Vietnam People’s Army launched the Tet Offensive during the Tet celebrations, the most important cultural celebrations in Vietnam. Attacks on shared religious holidays further occurred during both World Wars (with informal exceptions covered below) and can also be observed in the Russia-Ukraine war, where fighting continued through the shared religious holidays of Christmas and Easter, with Russia carrying out attacks on Palm Sunday most recently. Beyond the important and more well-known holidays, attacks on days that are generally considered sacred according to certain religions – such as Fridays for Muslims, Saturdays for Jews, and Sundays for Christians – are also more prevalent (Hassner, pp. 17, 32f.).

Of course, this correlation could be coincidental and the attacks might have been carried out on the specific date without any ulterior motive. It appears more realistic, however, that these days are picked because there was an expectation that the enemy forces would be less prepared and take longer to mobilize; also, the added insult and indeed sacrilege of attacking on a religious holiday may be expected to demoralize the adversary (as Hassner points out, none of these assumptions are necessarily correct, but that does not change the motivation itself, cf. pp. 12ff., 37).

Attacking the adversary on a religious holiday to take advantage of an unprepared military or to provoke religious outrage carries a distinct moral wrong – but does this correspond with a distinct legal prohibition to carry out such attacks? In other words: Is an attack that would otherwise be lawful under IHL prohibited because it was carried out on a religious holiday that is celebrated by a significant part of the adversary’s population?

Now Say, What Is Your Stance on Religion, IHL?

There is no written rule of IHL that explicitly prohibits attacking the adversary on religious holidays. Considering the apparent motives for attacking on religious holidays, however – gaining a military advantage by attacking a less-prepared and possibly demoralized, religiously offended enemy – a number of IHL rules come to mind that regulate similar scenarios, thus prompting the question whether such a prohibition might be implied in a more general rule.

Examining first rules particular to the protection of religion, it becomes quite clear that neither of those would cover and consequently prohibit attacks on religious holidays. This holds true first for rules protecting religious objects and religious personnel, such as Arts. 15, 53 AP I, which are also reflected in customary IHL for both international and non-international armed conflicts, see ICRC customary IHL study rules 27, 38. While the underlying rationale demonstrates that respect for the adversary’s religion is an important consideration in IHL, these rules are clearly limited to the protection of religious objects and personnel. The case is slightly more complicated for the customary rules reflected in Arts. 104, 127 of the ICRC’s study, which require parties to the conflict to respect convictions and religious practices. These customary rules are based, i.a., on Arts. 34–36 GC III, Arts. 58, 93 GC IV, and Art. 75 AP I and thus on rules which protect the religious freedom of persons who are in the hands of a belligerent party of which they are not nationals, because they are prisoners of war, detainees, or because their territory is under occupation. These rules are thus limited in scope, both regarding their material and personal field of application and they do not extend to general protection on religious holidays.

Regarding the background that enemy forces may be less prepared on such occasions, there is also a structural similarity between attacks on religious holidays and attacks on persons who for other reasons would not expect an attack. In this vein, one may consider some attacks deliberately exploiting the enemy’s unawareness towards an advantage as acts falling within the ambit of the prohibition of perfidy. Codified and defined in Art. 37 AP I, the prohibition seeks to protect armed forces who are betrayed in their trust not to come under attack. However, in its commentary on the prohibition as a rule of customary IHL (see rule 65), the ICRC identifies “the invitation to obtain and then breach the adversary’s confidence” as “the essence of perfidy”. It is difficult to see how the mere existence of religious holidays would invite the adversary’s confidence that it will not be attacked. Without the existence of additional factors, like a ceasefire agreement specifically for the period of religious holidays, the prohibition of perfidy does thus not prohibit attacks taking place on religious holidays; the same goes for the general obligation of complying with obligations under IHL in good faith, which does not create specific new obligations (cf. commentary to rule 64). At most, such attacks on religious holidays would thus constitute (permitted) ruses along the lines of codified IHL.

Is There a Customary Prohibition on Attacking on Holidays?

State practice that could support the existence of a customary prohibition on attacking the adversary on religious holidays dates far back – as is widely reported, British and German soldiers celebrated Christmas with a friendly football match on the battlefield as part of the so-called Christmas truce of 1914 (see, e.g., here, here, and here). The truce was unofficial, and in any event not carried by a sense of legal obligation. Yet, specific truces for religious holidays are not uncommon: In 1999, Slobodan Milosevic announced a unilateral Easter ceasefire, which was not accepted by the Allied NATO forces. By contrast, then US President Bill Clinton – who had rejected Milosevic’s Easter ceasefire – did stress the necessity of preventing armed conflict during Ramadan just one year earlier, stating that “[f]or us to initiate military action during Ramadan would be profoundly offensive to the Muslim world”. Again, the statement is not clearly carried by a sense of legal obligation, but rather seems to have been motivated by political considerations – Clinton continued to emphasize that military attacks during Ramadan “would damage our relations with Arab countries and the progress we have made in the Middle East.” Easter as well as Christmas ceasefires have been discussed multiple times in the Russia-Ukraine war, but were ultimately never implemented; recently, Russian president Vladimir Putin announced a unilateral Easter truce, which Russia reportedly did not adhere to, however (see here and here). Finally, the pope regularly calls for ceasefires to respect religious holidays, e.g., in 1999, 2023, and 2024.

Looking beyond individual states, there is also some limited practice of the UN Security Council concerning religious holidays. In 1994, the Security Council expressed shock in relation to an attack against a Mosque “during the holy month of Ramadan” (UN Security Council Resolution 904 (1994)). In 2024 and in relation to the conflict in Gaza, the Security Council demanded “an immediate ceasefire for the month of Ramadan” (UN Security Council Resolution 2728 (2024)).

Altogether, this practice underscores the commonly perceived moral wrong in initiating or continuing attacks on religious holidays. However, the practice is of limited value in identifying an independent prohibition to initiate or continue attacks on religious holidays. Instances in which truces or ceasefire agreements have been concluded or called for may just as well provide an argument against the existence of an independent customary prohibition: Even when the warring parties recognized the need to establish a particular truce to stop the hostilities for a specific period, this implies the legal opinion that a continuation of hostilities throughout that period would otherwise remain lawful under IHL. Instances where states stopped fighting without concluding a particular truce or ceasefire agreement are even more rare and could just as well be explained by extra-legal motives. Ultimately, it is the absence of condemnation in legal terms in the face of such attacks that speaks most clearly against the customary status of a prohibition on attacking on holidays.

Conclusion 

There is neither an explicit prohibition on attacking adversaries on religious holidays in treaty-based or customary IHL, nor does such a prohibition follow implicitly from another established rule of IHL. Given the extensive practice of attacking on religious holidays, the apparent moral wrong inherent in these attacks, and the respect IHL generally demonstrates for religion this result may surprise, but it appears to be firmly grounded in current IHL.