Here's a detailed description of ambassador Neville Henderson being received by the foreign ministry in Berlin in 1939. Perhaps the most famous example.

He came in looking very serious, shook hands, but declined my invitation to be seated, remaining solemnly standing in the middle of the room.

'I regret that on the instructions of my Government I have to hand you an ultimatum for the German Government,' he said with deep emotion

This site has a description of Ciano handing out Italy's declarations of war on June 10th 1940:

On 10 June, dressed as a major in the Regia Aeronautica, he handed the Allied ambassadors Italy's declaration of war

When did this formal (slightly awkward) practice of making an official "declaration of war" via an ambassador or foreign minister cease?

It seems as if it stopped in 1945 but am I right? Thinking of the major conflicts initiated by individual sovereign states since WW2, such as Iran-Iraq in the 1980s, China & India, India & Pakistan, the Six Day War, the Falklands, in those examples I am nearly certain there were no formal declarations of war of the kind Neville Henderson or Galeazzo Ciano delivered.

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    Are you talking about the United States specifically or any country? It sounds like you're referring to the U.S. but just want to make sure. Commented Oct 13, 2011 at 20:00
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    Declaring war did not cease. Commented Oct 13, 2011 at 21:00
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    I down voted because the question is/was erroneous. Formal declarations of war do continue to exist to this day. I remember that the USA declared war on Iraq in 2003 via their ambassadors in the UN. However, I cannot find a primary source for this. Commented Oct 14, 2011 at 10:13
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    @Sardathrion - No, the USA never declared war on Iraq. Our constitution specifies that only Congress has the power to declare war, and they never did that with Iraq. I believe the USA has not declared war on anybody since 1941.
    – T.E.D.
    Commented Apr 27, 2012 at 22:12
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    @T.E.D.: Close. The US declared war on Bulgaria, Hungary, and Romania on June 5, 1942. Reference Commented Aug 5, 2012 at 1:55

7 Answers 7


Theoretically, wars are still supposed to be declared. To quote the Hague Convention III of 1907:

The Contracting Powers recognize that hostilities between themselves must not commence without previous and explicit warning, in the form either of a reasoned declaration of war or of an ultimatum with conditional declaration of war.

However, after searching through some sources I have to agree with you - I cannot find any post-WWII war that has been formally declared. The last declaration of war I could find was Soviet Union to Japan in 1945.

Every war that the United States participated in after that was declared as "military engagement" or "police action". United Kingdom behaved similarly, and so did Soviet Union (I don't have a link but Soviet Union always "restored order" or supported a party on its request). I blame the Cold War, none of the sides wanted to admit that they were leading wars of aggression. Same tendency continues however, see for example 2008 South Ossetia War declared as "humanitarian intervention".

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    I always understood that since the UN was formed, no member state is allowed to declare war. Seems rather odd though as there has been plenty of fighting. Commented Oct 17, 2011 at 11:07
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    The UN bans the both the threat and use of force in international conflicts. Wonder how that's working out in practice?
    – none
    Commented Feb 29, 2012 at 17:07
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    Apparently the United States has only formally declared war 11 times senate.gov/pagelayout/history/h_multi_sections_and_teasers/…
    – ihtkwot
    Commented Mar 14, 2012 at 14:01
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    Democracies try to go to war without declaring a war, because it'd be politically very difficult.
    – quant_dev
    Commented Mar 17, 2012 at 16:06
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    @quant_dev - exactly. In the USA, a formal declaration of war requires an act of Congress - often very difficult politically to implement.
    – user2590
    Commented Jul 22, 2013 at 7:03

In fact formal declaration of war in many countries brings many practical legal consequences, which may include:

  • imposition of martial law

  • extraordinary powers for the head of state

  • ban on political parties and political activities as well as strikes

  • limitation of rights of foreign nationals, especially those of the enemy state

These consequences are not often desirable if a war does not affect the general population of the involved party. It is not needed to invest the president with special powers domestically, the enemy nationals living in the attacking state usually either neutral or supportive of the invasion (otherwise why they do not live at home?), the factories do not need criminally prosecute workers who miss workdays to operate normally etc.

The attacked party usually does not declare war because it makes possibility to avoid the full-scale conflict more difficult. Not having declaration of war makes easier for the attacking party to withdraw from the conflict.

Also declaration brings the impression that the war is conducted by a certain power rather than "international community" which is often desirable due to political reasons.


In his judgment in the Tokyo war crimes tribunal, Justice Radhabinod Pal claimed that while in the west there was a convention of declaring war before the resumption of hostilities, the east did not have anything similar. He also provided a number of examples of wars that had been fought without ever declaring war, which is available in the report. So it can be said that even before 1945 the rule was not followed very strictly.

  • See Pearl Harbour. The Japanese declaration of war was deliberately timed to not reach the White House before the attack was underway in order that no defense could be mounted.
    – jwenting
    Commented Jun 11, 2013 at 5:35

I think the main reasons are:

  • to attack surprisingly, even if the aggressor coordinates first shots with the minister,
  • to take off the guilt from the aggressor. For example, Nazi Germany in September 1939 were counter-fighting the Gleiwitz incident, as self-defence of course, and Poland was made the aggressor,
  • to cheat the democratic people that this is not the war but "military action" so they are less opposed,
  • especially when we would now be attacked by the country that we perform a "military action" against, this would be then the act of war (we're not at war now),
  • to bypass internal regulations. For example in the USA the war is declared by Congress, but the President can undertake "necessary military measures" eg. against Serbia or Libya,
  • to protect our spies against death penalty, which is in many countries made only during a war,
  • to prevent mass-media reporting our officials doing this "old-fashion stuff" and "playing diplomatic games" for tax-payers' money, while "many people are about to die",
  • to prevent opposition against "the governing party lead our country to war",
  • to ensure everyone else that we are also wanting peace and war is ugly,
  • Russia will not intern our ships when we are in military action with Serbia. That's also good for Russia, because they do not have to think about every US ship, A/C etc., how long it is in Russia and 48 hrs. have already passed or not,
  • we don't bother other Powers,
  • it's easier to find allies for "military action" than for war (from all the reasons above),
  • it's easier to have another country with "friend neutrality": you don't look what we do against Ruritania, and we don't look what you do with Curaguay,
  • it's hard to keep war in the whole world. This "military action" should be kept local, so we do not bother our opponent's ships and A/C -- but we should if this would be war,
  • during military action we can still perform trade with attacked country,
  • after the war we usually want some contribution, some territories etc. So we make peace with leaders that we presented declaration of war. In military action we don't want anything (it would be bad and imperialistic if we kill people to get money and territories), but we want to change the officials to our spies or fans (who then lower customs, give mining concessions, buyl 10000 ships from our shipyards etc.). During the war the officials can become heroes. So it's easier for the defending country to change its government than to just surrender the war,
  • (last not least) because it is in fact in modern world not necessary.
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    "to attack surprisingly," you can attack surprisingly and then declare war, as did Germany when invading the USSR.
    – Anixx
    Commented Jun 10, 2013 at 14:46
  • But if something goes wrong you can always say "oops pardon us, this was a mistake".
    – Voitcus
    Commented Jun 10, 2013 at 16:16
  • Agreed with @Anixx, quite often war is declared after the surprise military strike. Troops were landed in Iraq before war was officially declared. Japan declared war on USA right after Pearl Harbor. I think most of this can be summarized as saying that most people want a limited military conflict between governments, but not a full on war. With today's precision warfare, we try to take out the leaders of a government, not to blow everything up along the way.
    – Muz
    Commented Jun 11, 2013 at 4:25
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    I'd say the first shot fired is a very effective declaration of war :)
    – jwenting
    Commented Jun 11, 2013 at 5:36
  • @Muz: I would say, Japan declared war on the US simultaneously with Pearl Harbor. The Japanese ambassador was told to "drop in" on the Secretary of State just a few minutes after the attacks were scheduled to begin and announce the bombimg.
    – Tom Au
    Commented Jun 13, 2013 at 18:24

There are some exceptions, such as the 2005 Chad declaration of a state of war with Sudan.

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    Downvote: the link you gave doesn't mention an actual declaration of war, as a legal instrument. Just the Chad government saying to it's population it's in a "state of war". Not quite the same thing. Commented Dec 5, 2012 at 0:58

The reason why it seems that there are much less declarations of war in the second part of the 20th Century, is that most of the wars involving developed countries were not formally a war between two countries. Indeed, most were formally

Were no other state was officially present, or not recognised. In civil wars, other powers were sometimes supporting one of the side, but not officially at war themselves.

Nevertheless, there are still official declaration of wars, like the Chad against the Sudan in 2005 (and until 2010).

Due to the complexity of UN regulation, the formal declaration of war is not so trivial. The wars against terrorism are not officially against states, and thus no such declaration can be done. And generally the types of wars being fought have considerably changed.

One notable exception is that the USA should have declared war against Irak in 2003. But my recollection from the time, is that it wasn't made, to profit from a surprise attack, similar to the Japanese in 1941.

  • I listed some state v. state wars to show those are the kind I'm interested in. Of course civil wars and colonial wars are a separate thing. Commented Jul 6, 2015 at 20:57
  • @TeaDrinker indeed. But have you look at the link? How about Chad against Sudan? Thing is, since WWII, the way to do it, is to do it at the UN. I'm not sure I understand your comment...? Commented Jul 7, 2015 at 5:31

Pearl Harbor probably has some influence here. The Japanese wanted to present an official declaration of war, but screwed up with their timing. They were half an hour late; they declared war after the attack.

Which was actually worse. Now it was not only a sneak attack, but a planned sneak attack that would have given the defenders exactly as much chance: nothing.

After WW2 some wars were declared, but in general not very often. Surprise is far more valuable than good manners. Today if a war is actually declared, surprise doesn't matter anyway. For example, the Falkland were invaded without a declaration of war by Argentina, but England had all the time of the world for any diplomatic nicety you can think of.

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