During the Second World War, the United Kingdom was afraid of being invaded by the German army. To prepare for this possibility, the British government made a lot of plans to defend the country.
They built big walls and obstacles along the coast to stop enemy ships from landing on the beaches. These walls were called "pillboxes" and were made of strong materials to protect the soldiers inside.
They also created a team of people called the Home Guard to help prevent an invasion. These were regular citizens who volunteered to join and they were given weapons and trained to fight.
The government made sure there were enough supplies, like food and ammunition, in case the country went into a full-scale war. They also created blackout rules, which meant that all lights had to be turned off at night to make it harder for enemy planes to see and bomb cities.
Overall, the British did everything they could to make sure that they were ready to protect their country from an invasion.