Manifesto in front of British embassy in Warsaw after declaring war to Germany by Great Britain. Text on the banner says „Long Live England!” 3rd of September, 1939

Sending a battleship within range of the coastline of a hostile power without overwhelming air superiority would have been nuts, especially given the state of the Royal Navy's capital ships in September 1939.

Of the fifteen battleships and battlecruisers in operation at the onset of the war, only five would have been fast enough to take part in a raiding action against the German coast - Rodney, Nelson, Hood, Repulse, and Renown. But all of these fast units were needed to protect against German commerce raiders in case they broke out into the Atlantic and threatened supply lines to the Empire, as the remaining ten battleships weren't really fast enough to get involved in that sort of fight.

Secondly, as shown several times throughout the war, air and submarine power were both serious threats even to modern battleships. Prince of Wales, which was basically brand new, and Repulse were both sunk by aircraft off of Singapore. The older Royal Oak was sunk at anchor by a U-boat right at the start of the war. To add to these threats was the heavy mining of the North Sea, making it difficult to traverse.

So, the Royal Navy would have had to have sent the most valuable third of its capital ship fleet into range of overwhelming enemy air power, through minefields, and risking submarine attack, in order to shell some cities. This would have taken place before the Blitz, so it would have been a clear propaganda victory for Germany given the inevitable civilian casualties and collateral damage, and would have had minimal strategic value given that half of Germany's ports lay in the Baltic, but could have resulted in the destruction of all of the Royal Navy's most valuable capital ships. Yeah, great idea!

Britain was not ready to fight in September 1939, and France even less so, despite massive rearmament programmes. It's easy to say that the war could have been ended quickly by a decisive assault over the Maginot Line, but difficult to see how either the UK or France could have maintained that momentum with the state of their equipment and personnel.

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