“Accommodation” underscores the simple fact that whereas one chooses to collaborate, one does not at first choose to accommodate. In 1940, a mere handful of French either went abroad or went underground with the arrival of the Germans. As for the remaining 40 million or so, they had no choice — at least if they wished to survive — but to accommodate themselves to the reality of German rule. Unable or unwilling to tear themselves away from everything they knew, they unhappily subjected themselves to a world of unfamiliar constraints. “How could they,” Mr. Burrin wonders, “have avoided doing so?”

Does “accommodation” provide a better way to understand our own Vichy Republicans? Their situation is uncannily similar to that of the Vichy French. As any decently connected Washington reporter will tell you, many Republicans do not like having Mr. Trump in charge of their party, and will say so in private. But their political identity as Republicans runs at a level almost as deep as their national identity as Americans. Most Republican politicians could no more tear themselves away from the world that had formed and informed them than could the wartime French from their world. As Peter Wehner, a Times opinion writer and one-time Republican stalwart, observed: “The G.O.P. had been my political home since college, a party I was once proud to be part of, and a source of cherished relationships. Part of my identity was undoubtedly shaped by my party affiliation.” Those who have stayed in the party have had to accommodate themselves to the reality of Trump rule.

Accommodation means different things to different people in different contexts. And, far from being a static relationship, accommodation is a dynamic that is punctuated with choice, and thus demands constant attention. Jean-Paul Sartre, who himself made certain accommodations with the Vichy, captured this truth with the paradoxical claim that the French were never freer than they were under the Occupation. Making the wrong choice, or making no choice, could draw you closer to collaboration. For this reason, Mr. Burrin observes, the French had to calculate their concessions as precisely as possible, abstain from anticipating the occupier’s demands and adopt policies that committed their country’s future.

Inevitably, while some struggled not to slide down this slippery slope, others threw themselves down headfirst. Some made as few concessions as possible while others made as many concessions as the desire for either personal convictions, personal advancement or personal revenge required. Some held their noses while others held out their hands in welcome.

This observation applies with equal force to Vichy Republicans. Those who, like Mr. Wehner, chose not to quit the party with Trump’s arrival, condemned themselves to a different calculus of choice. A few have loudly condemned him. Others might laud the president in public while undermining him in private, while still others might see the president and his agenda as a vehicle they can steer toward a better purpose. And of course, many have embraced him in full.