Declarations of war by Great Britain and the United Kingdom Facts for Kids

A declaration of war is a formal statement made by a country's government. It tells the world that a state of war now exists between that country and another. It's like a formal announcement that a fight has begun.

In the United Kingdom, the power to lead the armed forces belongs to the King or Queen. However, the government and the Defence Council also help manage the armed forces. Over time, a special rule has developed: Parliament usually needs to agree before the UK goes to war.

There has been a long discussion about whether Parliament alone should decide if British forces go into a conflict. For example, in 1999, there was a try to make Parliament approve any war against Iraq. But the Queen at the time, Queen Elizabeth II, didn't allow the bill to be discussed. This was because it affected her special powers, known as the Queen's Consent. A law in 2010 also tried to make Parliament's approval necessary, but this part was removed.

Since the Second World War, the UK hasn't made any formal declarations of war. The last one was against Germany in 1942. Even without a formal declaration, the British Armed Forces have taken part in many conflicts. Today, many people think a formal declaration of war isn't really needed anymore. This is because of new international laws, like the Charter of the United Nations, which aim to prevent wars.

How a War Was Declared (Historically)
Declarations by Great Britain (1707-1801)
Declarations by the United Kingdom (1801-Present)
See also

How a War Was Declared (Historically)

Before the Second World War, there was a clear way to declare war. A letter from 1939 explains the process:

A special messenger would deliver the declaration of war to the enemy country's representative in London.
They would get a receipt to show the exact time it was delivered.
The messenger would also bring special passports for the enemy representative and their staff to leave the country safely.
Sometimes, an ultimatum (a final demand) would be sent first. This would say that if certain actions weren't stopped by a deadline, war would begin.
If the deadline passed without a good reply, the declaration would state that a state of war existed from that time.
Other government departments and representatives from friendly countries would then be told that war had been declared.

Declarations by Great Britain (1707-1801)

This table shows wars declared by the Kingdom of Great Britain after 1707 and before the creation of the United Kingdom of Great Britain and Ireland in 1801.

War or conflict	Opponent(s)	Initial authorisation	Declaration	Monarch	Prime Minister	Conclusion
War of the Quadruple Alliance	Spain	17 December 1718		George I	None	Treaty of The Hague, 17 February 1720.
War of Jenkins' Ear	Spain	23 October 1739		George II	Robert Walpole	Treaty of Aix-la-Chapelle, 18 October 1748.
War of the Austrian Succession	France	31 March 1744			Henry Pelham	Treaty of Aix-la-Chapelle, 18 October 1748.
Seven Years' War	France	17 May 1756	Declaration on France		Thomas Pelham-Holles	Treaty of Paris, 10 February 1763. British victory.
Seven Years' War	Spain	4 January 1762	Declaration on Spain	George III	Thomas Pelham-Holles	Treaty of Paris, 10 February 1763. British victory.
American Revolutionary War	France	17 March 1778	Declaration on France		Lord North	Treaty of Versailles, 3 September 1783.
American Revolutionary War	Spain	1779	Declaration on Spain			Treaty of Versailles, 3 September 1783.
Fourth Anglo-Dutch War	Dutch Republic	December 1780	Declaration on the Dutch Republic			Treaty of Paris, 20 May 1784.

Declarations by the United Kingdom (1801-Present)

This table lists declarations of war since the creation of the United Kingdom in 1801. In 1927, the United Kingdom of Great Britain and Ireland became the "United Kingdom of Great Britain and Northern Ireland."

War or conflict	Opponent(s)	Initial authorisation	Declaration	Monarch	Prime Minister	Conclusion
Napoleonic Wars	France	18 May 1803		George III	Henry Addington	Treaty of Paris (1815) and Congress of Vienna
Crimean War	Russia	28 March 1854	Declaration on the Russian Empire	Victoria	Earl of Aberdeen	Treaty of Paris, 30 March 1856
Bhutan War	Bhutan	November 1864	Declaration on Bhutan		Viscount Palmerston	Treaty of Sinchula, 11 November 1865
Anglo-Zulu War	Zulu Kingdom	18 March 1879	Ultimatum by Sir Henry Bartle Frere		Benjamin Disraeli	The war ended the Zulu nation's independence.
Anglo-Zanzibar War	Zanzibar	27 August 1896	Ultimatum by Rear-Admiral Harry Rawson		Marquess of Salisbury	The war replaced Khalid bin Barghash as Sultan with Hamoud bin Mohammed, leading to the abolition of slavery.
First World War	Germany	4 August 1914	Declaration on Germany	George V	H. H. Asquith	Armistice with Germany, 11 November 1918. Treaty of Versailles, 28 June 1919.
	Austria-Hungary	12 August 1914	Declaration on Austria-Hungary			Austria: Treaty of Saint-Germain-en-Laye, 10 September 1919. Hungary: Treaty of Trianon, 4 June 1920.
	Ottoman Empire	5 November 1914	Declaration on the Ottoman Empire			Treaty of Sèvres, 10 August 1920.
	Bulgaria	15 October 1915	Declaration on Bulgaria			Treaty of Neuilly-sur-Seine, 27 November 1919.
Second World War	Germany	3 September 1939	United Kingdom declaration of war on Germany (1939)	George VI	Neville Chamberlain	Treaty on the Final Settlement with Respect to Germany, 12 September 1990. The Potsdam Agreement on 2 August 1945 agreed the subdivision of Germany following the surrender on 8 May 1945. Austria was part of Germany when War was declared, and was formally re-established by the Treaty of Vienna on 15 May 1955.
	Italy	11 June 1940	Declaration on Italy		Winston Churchill	Armistice with Italy, 3 September 1943. The final peace treaty between Italy and the Allies was signed in Paris on 10 February 1947.
	Finland	5 December 1941	Declaration on Finland			Moscow Armistice, 19 September 1944. The final peace treaty between Finland and the Allies was signed in Paris on 10 February 1947.
	Hungary	5 December 1941	Declaration on Hungary			The final peace treaty between Hungary and the Allies was signed in Paris on 10 February 1947.
	Romania	5 December 1941	Declaration on Romania			Armistice with Romania, 12 September 1944. The final peace treaty between Romania and the Allies was signed in Paris on 10 February 1947.
	Japan	8 December 1941	Declaration on Japan			Treaty of San Francisco, 8 September 1951. This followed the Surrender of Japan on 15 August 1945 and the Occupation of Japan which began on 28 August 1945.
	Bulgaria	13 December 1941	Declaration on Bulgaria			Armistice with Bulgaria, 28 October 1944. The final peace treaty between Bulgaria and the Allies was signed in Paris on 10 February 1947.
	Thailand	25 January 1942	Declaration on Thailand			Anglo-Thai Peace Treaty, 1 January 1946