The Gestapo called her “The White Mouse” for the way she deftly avoided their traps.

Nancy Wake, 98, who died of an infection Aug. 7 in London, was one of the most effective and cunning British agents working in German-occupied France during World War II.

A sultry glamour girl before the war, she married a French playboy industrialist whose tastes, like hers, ran to caviar and champagne midmorning and love in the afternoon. They were living in southern France when the war ignited.

She hid downed Allied servicemen at her home and led them over the Pyrenees to the safety of neutral Spain. She later helped organize thousands of French resistance fighters known as the Maquis, by meeting Allied arms drops, distributing weapons and training 7,000 partisans in preparation for the Normandy invasion.

She earned decorations from the British, French and American governments; she was belatedly honored in Australia, where she had grown up. Exact figures are hard to establish, but she was reported to have helped save many hundreds of lives.

Nancy Wake, shown in 1945, was a spy and became one the Allies' most decorated servicewomen for her role in the French resistance during World War II. (Australian War Memorial/ASSOCIATED PRESS)

Max Hastings, a British journalist and military historian, described her an “ardent warrior, possessed of an endless appetite for sensation.”

As her involvement in the war deepened, Ms. Wake was trained by the British to kill with her bare hands (she delivered a fatal karate chop to a sentry at an arms factory), parachute into enemy-held territory and work a machine gun.

She chomped on cigars and bested guerrilla fighters in drinking bouts. She traveled nowhere without her Chanel lipstick, face cream and a favorite red satin cushion.

“She is the most feminine woman I know until the fighting starts — then she is like five men,” a colleague in the French resistance once said.

With her highly motivated force, Ms. Wake planned and executed a successful raid on a Gestapo garrison and an arms factory in central France in 1944.

The Gestapo placed a large bounty on her head. That she evaded capture and death added to her mystique; one-third of the 39 women serving in the British Special Operations Executive in France did not come home.

She was dauntless. When a German counterattack against the Maquis disrupted lines of communication, Ms. Wake covered 200 kilometers by bike over hostile ground to get and receive crucial messages. She slept in haystacks or in the open during her 72-hour journey, which resulted in reestablishing radio contact with London.

The nature of her work made Ms. Wake cautious. Three French women came to her attention for possibly being spies. Under her interrogation, she became satisfied two were telling the truth. She sentenced the third to death by firing squad.

“I was not a very nice person,” Ms. Wake told an Australian newspaper in 2001. “And it didn’t put me off my breakfast. After all, she had an easy death. She didn’t suffer. I knew her death was a lot better than the one I would have got.

“And if I hadn’t done it,” she added, “and she had got away and reported to the Germans what the Maquis were up to, how could I have ever faced the families of the Maquisards we lost because of it? It was definitely the right thing to do.”

Nancy Grace Augusta Wake, the youngest of six siblings, was born in Wellington, New Zealand, on Aug. 30, 1912. Her father, a journalist, abandoned the family in Sydney. He also sold the family’s home, forcing his wife and their children to find new lodgings.

Ms. Wake left home at 16 and, buffered by a small inheritance from an aunt, booked passage to England.

In London, she bluffed her way into journalism by telling a Hearst newspaper executive that she was fluent in Egyptian— Egypt being a favorite topic of his. She wrote shorthand gibberish that resembled hieroglyphics and passed it off as the language.

The news executive sent her to Paris as a roving European correspondent, where she said she was awakened to the growing atrocities of Adolph Hitler.

In 1939, she married Henri Fiocca, heir to a Marseille shipping concern. She later told the Daily Telegraph: “He was tall. He could dance the tango. And if you dance the tango with a nice, tall man, you know what eventually will happen, don’t you?”

After the Germans rolled into France in 1940, she became an ambulance driver and gradually deepened her involvement in the escape line from her home in Marseille. She hid people on the run, paid exorbitant bribes to prison guards to free those captured by the local authorities and became a dependable courier for the resistance.

She became a threat to the Germans, and her handlers advised her to make her way to England via Gibraltar. Her husband promised to come after settling family business but was shot by the Nazis after refusing to reveal her whereabouts.

With the escape route in constant peril and Germans patrolling the trains, it took several tries before Ms. Wake was able to make it to Spain on the back of a coal truck. She had earlier been forced to jump from a slow-moving train, drawing the fire of German soldiers.

She arrived in England in June 1943, then underwent eight months of training in the Special Operations Executive. She was subsequently parachuted into the Auvergne region of central France as a liaison between London and the Maquis.

After the war, Ms. Wake tried to find a job that suited her energies. She ran unsuccessfully for political office in Australia, returned to England to do intelligence work and, in 1957, married former British air force pilot John Forward. He died in 1997. She never had children.

In recent years, she lived in a nursing home for retired veterans. She passed much of the day clutching a gin and tonic at the nearby hotel bar, the same watering hole where she had her first “bloody good drink” after the war.

Ms. Wake was the subject of two biographies in addition to her 1985 memoir. A TV miniseries aired in the late 1980s; she was typically scornful of its factual liberties.

“For goodness sake, did the allies parachute me into France to fry eggs and bacon for the men?” she asked. “There wasn’t an egg to be had for love nor money, and even if there had been, why would I be frying it when I had men to do that sort of thing?”