In the late spring of 1940, German forces invaded Belgium and France and pushed most of the British army onto a beach in the French coastal town of Dunkirk. Neville Chamberlain, the British prime minister best known (then and still) for his policy of appeasing Hitler, was replaced by Winston Churchill, whose first weeks as head of the government — culminating in the Dunkirk evacuation — are the subject of “Darkest Hour,” Joe Wright’s new film. (The evacuation itself was reconstructed in Christopher Nolan’s “Dunkirk,” released in July.)

Considered as history, “Darkest Hour,” written by Anthony McCarten (“The Theory of Everything”), offers the public a few new insights and details about the practice of statecraft in a time of crisis. Churchill is disliked by many of his colleagues in the Conservative Party (notably Chamberlain and his vulpine sidekick, Viscount Halifax) and distrusted by King George VI. The political situation is shaky, the military reports dire. The new prime minister, a man of large emotions and larger appetites, who drinks whiskey with breakfast and is rarely without a cigar, is plagued by frustration and doubt as he tries to navigate between two bad options. Will Britain enter into a ruinous war or submit to humiliating and most likely temporary peace on terms dictated by Hitler?