British preparations included tank traps, obstacles and local defenses developed by Home Guard members with First World War experience. The Petroleum Warfare Division explored ways to use Britain's large fuel stocks in explosive and incendiary defenses. The Royal Navy practiced night firing and bombarded places where invasion craft assembled, while British bombers also attacked those concentrations. Losses from these attacks helped prompt Hitler's September instruction to disperse the assembled craft. Concrete positions and pillboxes continued to multiply, making rapid progress inland doubtful even if German troops reached shore.
Notable Point · 39:36-41:10
Fortifying Britain and attacking the invasion fleet
British defensive construction developed alongside naval bombardments and bomber attacks on the assembly points for German landing vessels.