A Molotov cocktail is a hand-thrown incendiary weapon consisting of a frangible container filled with flammable substances and equipped with a fuse. In use, the fuse attached to the container is lit and the weapon is thrown, shattering on impact. This ignites the flammable substances contained in the bottle and spreads flames as the fuel burns.

British anti-invasion preparations of the Second World War entailed a large-scale division of military and civilian mobilisation in response to the threat of invasion by German armed forces in 1940 and 1941. The British Army needed to recover from the defeat of the British Expeditionary Force in France, and 1.5 million men were enrolled as part-time soldiers in the Home Guard. The rapid construction of field fortifications transformed much of the United Kingdom, especially southern England, into a prepared battlefield. Sea Lion was never taken beyond the preliminary assembly of forces. Today, little remains of Britain's anti-invasion preparations, although reinforced concrete structures such as pillboxes and anti-tank cubes can still be commonly found, particularly in the coastal counties.