Britain is working on a comprehensive national war-readiness plan to mobilize the entire country in the event of conflict. The initiative revives elements of the historic "Government War Book," a framework first developed during World War I and maintained through the Cold War.

The Cabinet Office is spearheading the cross-government effort to update the war book for modern threats. The plan aims to coordinate responses across the military, police, hospitals, industry, and the public. Critical infrastructure, including energy grids, water supplies, and transport networks, will be prioritized for resilience against hostile actions beyond hybrid threats.

Air Chief Marshal Sir Richard Knighton, head of the Armed Forces, confirmed the development in an interview published on April 10. He emphasized the need to educate the public about emerging threats and prepare civilians for a potential active role in national defense. "That requires us to educate ourselves and help the population understand some of those threats," Knighton said.

The original war book outlined detailed mobilization steps, such as rationing supplies, clearing hospitals, and closing schools. It was abandoned in the early 2000s after the collapse of the Soviet Union reduced perceived risks. Now, with global tensions rising, including Russian aggression and vulnerabilities to long-range missiles from Iran, officials argue that decades of relative peace can no longer be assumed.

This effort builds on the government's 2025 strategies. The Strategic Defence Review called for a "whole-of-society" approach, including a Home Defence Programme led by the Cabinet Office. The National Security Strategy and Resilience Action Plan stressed the need to protect critical infrastructure and enhance public awareness through initiatives such as the 'Prepare' website and the UK Resilience Academy.

Former Defence Secretary Ben Wallace highlighted the urgency, noting the UK lacks defenses against certain missile threats. He urged open discussions about reservist call-ups and shifted priorities. "It’s the point about this readiness … leveling with the public that we're going to have to think differently," Wallace said.

Parliamentary committees have criticized delays in related plans, such as the 10-year Defence Investment Plan, and called for greater transparency on civil-military alignment. The government has pledged to raise defence spending to 3.5% of GDP by 2035 and introduce a Defence Readiness Bill when parliamentary time allows.

Knighton welcomed the Cabinet Office's work, stressing resilience in infrastructure renewal. The plan addresses NATO commitments under Article 3 for self-defense capacity amid a deteriorating security environment.