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Home defence: What is the War Book?

Beginning in the early 20th century, government plans for how the country would respond to an attack on the UK mainland were contained in what was called the “War Book”. During the Cold War, these plans focused on preparing for a nuclear attack and specified what actions ministers, officials and local authorities should take during a period of war. The end of the Cold War, and the diminishing threat of invasion or attack, meant the traditional War Books were archived.

However, the war in Ukraine, among other things, has resurrected the possibility of conflict involving the UK. This has prompted the government to resurrect the “War Book” as part of its wider Home Defence programme. These are separate to military plans for how the armed forces would respond to any attack, but reflect the government’s ‘whole-of-society’ approach to defence and national security.       

This briefing explores the origins and evolution of the War Book, why they were shelved, and what the government has said about a new iteration.

It forms part of a series of Commons Library papers on defence readiness, civil preparedness and resilience ahead of expected defence legislation later in the parliamentary session.

What was the War Book?

Early 20th century planning

In 1912, two years before the outbreak of the First World War, Prime Minister Asquith told the House of Commons that the government had created a War Book, which set out the responsibilities for each government department in the event of a war. He explained why such a book was necessary:

It is a curious thing there has never been, in all the centuries in which we have carried on with more or less success our military and naval operations, a body which was charged with the special duty of providing in the time of peace for the co-ordination of departmental action on the outbreak of war.

Drawn up by the Committee for the Co-ordination of Departmental Action at the Outbreak of War (a sub-committee of the Committee of Imperial Defence which was responsible for defence planning), the book contained all the “Proclamations, Orders in Council, Letters, Telegrams, Notices” and so on that might be required upon the outbreak of a war. Prime Minister Asquith said that “every possible provision has been made to avoid delay in setting in force the machinery in the unhappy event of war taking place”.

The National Archives has hard copy records of the Committee for the Co-ordination of Departmental Action at the Outbreak of War (CAB 15): there are 39 volumes covering the period 1911 to 1939. These include a 1928 Cabinet Office dossier entitled “Supreme Control in War”.

The Cold War period

After the Second World War, the Cabinet Office started preparing a fresh War Book which specified what actions ministers and officials should take during a period of war. These were assembled in three parts: pre-Precautionary Stage matters, the Precautionary Stage, and War. In addition, each Department of State was advised to maintain a departmental War Book to set out sector-specific actions. The dominant theme of Cold War planning was the potential for nuclear attack.

The National Archives says the War Books were subject to a virtually continuous process of revision and amendment.

In June 2009 the government released a copy of the War Book that was used during the Cold War. The Guardian reported at the time that the document, over 16 chapters, set out “precise plans and instructions” for officials during the build up to an international confrontation and a nuclear war. The historian Lord Hennessey of Nympsfield said what was surprising was the “width and magnitude of it” and the detail contained to “get the nation from a peacetime footing to a total war footing”.

The Guardian provided more detail of the plans:

The country would have been divided into 12 regions, each governed by cabinet ministers with wide powers, aided by senior military officers, chief constables and judges and based in bunkers. Other senior figures would have retreated to a central government shelter under the Cotswolds.

The National Archives explains that a key planning assumption of the time was that at the outset of an emergency a new Emergency Powers (Defence) Bill would be presented to Parliament. As a precedent, the Emergency Powers (Defence) Act 1939 gave the government “special powers to take almost any action necessary to carry out the war successfully.” The act stayed in force until 1964.

Journalist Julie McDowall’s book Attack Warning Red: How Britain prepared for nuclear war sets out how the government established “countless agencies and civil administrations” covering all aspects of British life in preparation for a nuclear war.

The National Archives holds a run of War Books in hard copy (CAB 175).

Why was it stopped?

The War Book was discontinued with the collapse of the Soviet Union and the end of the Cold War in the 1990s. In 2015, the government said that the traditional War Books had been archived since the end of the Cold War and that “details of specific plans and arrangements are not held together in one compendium”.

Instead, the government explained, separate arrangements for civil defence and emergency planning were combined and underpinned by the Civil Contingencies Act 2004. Further background on this can be found in Commons Library briefing Dealing with civil contingencies: Emergency planning in the UK.

Why has it been renewed?

In April 2024, Sky News reported that a paper was circulating in Whitehall (central government) that “examines what can be learnt from an old but comprehensive system of plans called the government war book - now sitting in the National Archives - that once detailed how the UK would transition from peace to war” (the report includes a version of the book).

As set out above, the government has long had “well-developed contingency plans to respond to a wide range of eventualities” underpinned by the Civil Contingencies Act.

Increasing insecurity

However, increasing global insecurity and the threat posed by Russia since its annexation of Crimea in 2014 and full invasion of Ukraine in 2022 has prompted successive governments to prioritise and accelerate preparations for a possible war. In April 2024 the then Defence Secretary, Grant Schapps, warned: “in five years’ time we could be looking at multiple theatres involving Russia, China, Iran and North Korea”. More recently, in June 2026, then Prime Minister Keir Starmer warned “there could be an attack by Russia on NATO as soon as 2030”.

Prioritising national resilience

One of the main conclusions of the government’s 2023 Integrated Review refresh was the need to strengthen the UK’s domestic resilience. The accompanying Defence Command Paper announced plans to work across government to “plan and test how we would better identify vulnerabilities, and exercise our systems, to secure and defend the homeland in times of war”.

The 2025 Strategic Defence Review and National Security Strategy emphasised the importance of societal resilience and protecting the critical national infrastructure that underpins much of how the UK functions.

The government’s 2025 Resilience Action Plan set out its approach to increasing the UK’s resilience against a wide range of risks. The government also published a National Risk Register, the public version of the National Security Risk Assessment (NSRA), which identifies and assesses the most serious risks facing the UK. Included in the National Risk Register 2026 are the risk of a conventional armed attack on the UK mainland or against a NATO ally (most risks are not related to military threats).

As part of the action plan, the government committed to making an annual statement to Parliament on the current state of preparedness. In July 2026, the then Chancellor of the Duchy of Lancaster, Darren Jones, said that the government has been “updating the government War Book” and “increasing the emphasis on aligning military and civilian efforts if international hostilities affect the UK”. He also said the government had been accelerating its Home Defence planning.

The Home Defence Programme

In August 2024 the government established the Home Defence Programme to “build the UK’s resilience to any potential escalation to conflict”. The then Security Minister Dan Jarvis explained what the purpose of the programme would be and how it was informed by other plans, saying:

It is an evolving and enduring programme of work which provides defence, security and resilience planning, focused on aligning military and civil effort in the event of a period of crisis and international hostilities affecting the UK, informed by and reflecting the recommendations from government strategies, including the Strategic Defence Review, National Security Strategy and Resilience Action Plan.

The government said, in its Resilience Action Plan implementation report published in July 2026, that as part of this programme:

The UK government will accelerate departmental planning and oversee work across government to update central crisis protocols, traditionally known as ‘War Books’, to set out how departments would respond to conflict and threats against the UK mainland. 

Nationwide exercise

The government is planning to test these plans in what it calls the “largest UK home defence exercise in several decades”, known as Exercise Albiston Shadow, in 2027. This will involve ministers and hundreds of officials from across government and the public sector in a multi-day exercise that will test “government preparedness for hybrid attacks against the UK”.

The government has a dedicated website with information for the public about preparing for emergencies. Prime Minister Andy Burnham is reportedly planning a publicity campaign to advise the public on how to prepare for severe disruption from events such as extreme weather or cyber attacks.

More information on the government's plans to prepare the UK for a crisis or conflict can be found in Commons Library briefing What is a 'whole of society' approach to defence and security?

New legislation forthcoming

The Strategic Defence Review recommended that the government should introduce a Defence Readiness Bill giving it “powers in reserve to respond effectively in the event of escalation towards a war involving the UK or its allies”. 

In July 2026, Luke Pollard, Minister of State, Ministry of Defence, said that the government “intends to bring forward this legislation later in this Parliament”.

In addition, in July 2026, the government launched a call for views on the upcoming review of the Civil Contingencies Act which is due in 2027. Specifically, it is asking whether current resilience structures “remain fit for purpose”. The responses may inform if and how the government proposes to amend the Civil Contingencies Act.

When will the War Book be ready?

In May 2026, Al Carns, then Minister for the Armed Forces, said that the Cabinet Office is “moving towards these war books by the end of the year” so that “across government but also right down into our local authorities, people understand their role in a time of crisis”.

The government has not indicated whether these plans will be publicly available. The wording of the July 2026 press release for the updated National Risk Register suggested they will remain classified: “Under the Home Defence Programme, classified government crisis plans, commonly known as the “War Books” are also being updated”.

The government is also working on sector-specific strategies, with plans to publish a Transport Resilience Strategy and Energy Resilience Strategy in 2026. Previous sector-specific strategies include the Biological Security Strategy, the Pandemic Preparedness Strategy and the Energy Sector Cyber Security Strategy.

Parliamentary scrutiny

Select committees of both Houses of Parliament have opened inquiries into national resilience in 2026:

• The House of Lords Select Committee on National Resilience, appointed in January 2026, opened in inquiry into national preparedness and resilience in March 2026.
• The Joint Committee on the National Security Strategy opened an inquiry into societal resilience in April 2026.
• The House of Commons Defence Select Committee launched an inquiry into the UK’s resilience and preparedness for conflict in July 2026.

On 14 July 2026, Lord Harris of Haringay (Lab), the chair of the National Preparedness Commission (an independent body), led a debate in the House of Lords asking the government about progress made towards drafting the Defence Readiness Bill.