Dina Temple-Raston is NPR’s counter-terrorism correspondent and is the author of four non-fiction books including “A Death in Texas” and “The Jihad Next Door.”

If someone had asked me to choose figures in national security, dead or alive, to include in a small dinner party, Eleanor Roosevelt and Fiorello La Guardia probably wouldn’t have jumped to mind. To be sure, there are plenty of other reasons to include the two of them at the table, but before I picked up Matthew Dallek’s immensely readable “Defenseless Under the Night,” I wouldn’t have said that national security was one of them.

“Defenseless” is a meticulous account of an epic battle that set Roosevelt, the first lady, against La Guardia, the mayor of New York, as the two created the country’s first Office of Civilian Defense (OCD), the precursor to what we know today as the Department of Homeland Security. Their differences were stark and revolved around the very meaning of civil defense in the run-up to World War II. Roosevelt was convinced that the best way to defend America was to ensure that a fifth column could never get a toehold. As she saw it, if citizens were housed, clothed and fed, they’d never consider embracing fascism. La Guardia, for his part, thought such an enterprise was too soft. The best defense against Hitler, he reasoned, was to militarize ordinary Americans and create a citizens’ army that could protect the home front as a fourth military branch.

Long before the bombing of Pearl Harbor, Dallek writes, the U.S. military was agitating for a battle-ready America. The argument at the time was that Hitler was able to march across Europe because its citizens were complacent. La Guardia vowed and, to a degree, President Franklin Roosevelt agreed that America could not afford to make the same mistake. Military leaders began recruiting thousands of farmers, housewives and shopkeepers to run invasion drills up and down the Eastern Seaboard, and dispatching ordinary citizens to stand in hundreds of watchtowers along the Atlantic and to record and track planes buzzing the hills around them. The Army started running air-raid drills, Dallek writes, to make clear that “the contagion of European war could spread to communities long thought safe from such microbes.”

Playwright Archibald MacLeish added to the hysteria with his radio drama “Air Raid.” “The show started with children at play,” Dallek writes. “Sirens whined. Bombs whizzed through the air. Children screamed. . . . All of these radio dramas, coupled with real-world signs that Europe stood on the brink of a catastrophe, created a mood within the United States that made tales of mass panic so believable. . . . People wondered how rational thought would survive when millions of citizens felt besieged with a dread of modern life. Americans asked how democracy would withstand the unprecedented power of Hitler’s military might and fascist appeal.”

"Defenseless Under the Night: The Roosevelt Years and the Origins of Homeland Security" by Matthew Dallek (Oxford Univ. )

Eleanor Roosevelt was convinced that her remarkable relationship with the American people — a kind of soft power on steriods — would prevent that from happening. She encouraged them to write her letters so she could solve their problems. The poor wrote to her about needing winter coats or medical care or better housing, and then were surprised to discover that the first lady not only read their letters but responded to them as well. Ordinary citizens asked her to find them roles — paid and unpaid — to help protect the nation.

It was in those letters that she saw the basis of a grand bargain: If Americans were willing to create a bulwark against Hitlerism, as she called it, then the government was duty bound to provide Americans with tangible evidence that confirmed why democracy was better. That meant not just equal rights for African Americans or equality for women — both of which she championed — but also the enactment of a broader social contract in which even the poor and working classes would feel that the government was caring for them.

Roosevelt believed the solution lay in having Americans simply live their values. One of her most controversial proposals of 1940 was for Congress to pass New Deal-type legislation that mandated national service for all Americans. These social soldiers, Dallek writes, would acquire “new skills, doing work that benefited their communities.”

“We have too long taken our freedom and liberties for granted and have given nothing in return,” she explained. Critics on the right said the plan smacked of totalitarianism; those on the left saw it as compulsory military training. “Her proposal had no chance in Congress, Dallek writes, “but her campaign both stoked and reflected the grassroots disquiet” in the country.

La Guardia, from his perch inside New York’s City Hall, saw civil defense as an extension of what cities — including his — were already doing. By his reckoning, to fight the enemies goose-stepping their way across Europe, America needed to create a government-civilian partnership that essentially militarized the lives of ordinary Americans. “He proposed training big city workers as volunteer firefighters and teaching them to handle a chemical weapons attack,” Dallek writes. “He recommended distributing gas masks to 50 million civilians, putting a mobile water pump on every city block, and establishing five volunteer fire brigades for every city brigade.”

La Guardia’s view undoubtedly grew out of his time as an airman in World War I. During the war, La Guardia trained U.S. and Italian pilots, flew combat missions, survived plane crashes and emerged with a deep-seated fear of the power of air campaigns. He studied the effects of air power on the war and after the armistice returned to the United States a pacifist. He argued that in any new war, “the civilian population in large and industrial centers and distant from the battle line [would] suffer more than the military forces in actual conflict.”

As a result, La Guardia’s vision for the OCD — like the mayor himself — was bold. Among other things, he wanted the head of the new office to have the authority to establish a national police force, something he thought could serve “as a fourth military branch.” La Guardia envisioned millions of civilians enlisted in a quasi-army. Mayors and governors would need to adopt civil defense plans set out by the OCD.

Eventually, it was less their competing visions for civil defense than good old-fashioned politics that led to the unraveling of the Roosevelt -La Guardia partnership. In 1942, the president relieved them both of their jobs at the OCD.

The first lady had critics who said her social defense was nothing more than social engineering, but she had been able to weather their objections. In the end, it was her decision to hire a friend, dancer Mayris Chaney, to lead a dance program to build children’s morale that forced the president to let her go. She had offered Chaney $4,600 a year to lead the program, a sum that seemed astronomical at the time. “Chaney’s salary affronted Americans who were being bombarded with calls to sacrifice their time (and, in some cases, risk their lives) in defense of their democracy for little or no pay,” Dallek writes. Almost overnight, Roosevelt became, in the words of one columnist at the time, the “most discussed” person in America. (Back then, as opposed to now, apparently, that was a death knell for a political figure.)

By early 1942, La Guardia was under fire, too. Critics blasted him for neglecting his work as mayor of New York (he never stepped down from that job) to run home defense. What’s more, the fearmongering that had become his signature in the run-up to the war now proved to be too much. “His inflammatory rhetoric did more to stoke mass fears of enemy attacks than unite the public behind a sensible war strategy,” Dallek writes.

The president concluded that La Guardia, too, had to go. He accepted his letter of resignation just days after the first lady stepped down.

While Roosevelt and La Guardia both lost their jobs, Dallek makes clear that the epic battle between them wasn’t without purpose: They ignited an important conversation about liberalism and its role in times of crisis. And while they never really found the perfect balance between civil liberties and national security, they made sure that people would discuss it for decades to come — perhaps even at dinner parties.

Defenseless Under the Night
The Roosevelt Years and the Origins of Homeland Security

By Matthew Dallek

Oxford. 340 pp. $29.95