Christopher Nolan's blockbuster film Dunkirk tells the story of one of history's most daring military feats. Operation Dynamo saw the combined effort of civilians and the armed forces to evacuate over 300,000 stranded allied troops from a beach in France during the Second World War.Like so many British families, the film's cast have connections to a military past, as discovered in Findmypast's extensive records. Harry Styles' great-grandfather: One Direction singer Harry Styles made his acting debut in Dunkirk, perhaps inspired…