DOVER, England — Few moments in modern British history are more iconic than the evacuation of the British expeditionary force of nearly 340,000 troops in the spring of 1940 from the beaches of Dunkirk, 22 miles across the Channel from the white chalk cliffs that overlook this ancient port town. At the time, Winston Churchill called it “a miracle of deliverance.”

Beneath azure blue skies on Sunday, an intrepid band of Englishmen tried to stage a scaled-down rerun of the “little ships,” hundreds of private craft that joined the Royal Navy in the improbable 1940 rescue, saving hundreds of thousands of British, French and Canadian soldiers to fight on against Nazi Germany.

This time, the effort centered on a group of men in a flotilla of inflatable speedboats who set out from Dover to ferry some of their stranded compatriots home from the cross-Channel rail-and-ferry chaos created by the cloud of volcanic ash that has shut down much of Europe’s air traffic.

British newspapers have calculated that the shutdown has stranded up to a million British travelers, counting those whose outbound flights have been canceled and those abroad trying to get home.

But after hours of fruitless negotiation, the organizers of the modern evacuation venture were defeated. The opposing force on this occasion was a small regiment of unimpressed French harbor and immigration officials, who met the Englishmen and their 30-foot boats in the harbor at Calais with a resolute “Non!”

After hours of appeals through diplomatic channels for an easing of the French veto, the organizers on the dockside in Dover abandoned the effort.