Elizabeth McIntosh in Kunming, China, during World War II. (Courtesy of The OSS Society)

Elizabeth McIntosh, who conjured lies in the line of duty for the Office of Strategic Services and as an author wrote about the women who used their brains — and sometimes their bodies — to help that spy agency in World War II, died June 8 in Lake Ridge, Va. She was 100.

The cause was a heart attack, said Alice A. Booher, her legal representative.

The daughter of a sportswriter, Mrs. McIntosh grew up in Hawaii and followed her father into journalism. She reported on women’s issues for the Scripps Howard news service but grew restless after having witnessed the Japanese attack on Pearl Harbor on Dec. 7, 1941.

A family acquaintance with connections to the OSS, which later evolved into the CIA, asked her, “Wouldn’t you like to get into something interesting like. . .’ You know, he didn’t say ‘spying,’ but he just said, ‘more interesting maybe than the work you’re doing.’ ”

She joined the OSS in 1943 and completed field-agent training in interrogation techniques, clandestine meetings and use of firearms. But cloak-and-dagger espionage or Mata Hari-style boudoir intrigue would not be her legacy.

Elizabeth McIntosh in 2011. (Katherine Frey/THE WASHINGTON POST)

Instead, her fluency in Japanese and background as a newspaperwoman made her ideal for “morale operations” in Asia, also known as “black” propaganda — spreading authentic-sounding misinformation designed to demoralize and confuse the enemy.

Stationed in New Delhi and later Kunming, China — where she befriended the future chef Julia Child — she participated in efforts to forge fake letters and documents as well as pamphlets and newspaper stories with realistic-seeming tales of suffering on the Japanese mainland.

Such accounts — of starving youths and young women so traumatized by bombing that they were unable to bear children — reached Japanese troops by radio, airdrop, mail and other forms of subterfuge.

Japanese soldiers were known to be honor-bound to fight to the death, and Mrs. McIntosh played a role in falsifying instructions designed to induce them to surrender more quickly in Burma toward the end of that campaign. According to an official OSS history, the forgery was successful in vastly reducing Allied casualties.

On another occasion, Mrs. McIntosh delivered an explosive masquerading as a lump of coal — the device was dubbed “black Joe” — to a Chinese operative of the OSS.

The agent took the dynamite aboard a train ferrying Japanese soldiers, and waited for the opportune moment to toss it into the engine before jumping to safety. The train blew up as it crossed a bridge.

Recounting the story to The Washington Post in 2011, she confessed to some initial guilt over the many deaths. But she quickly reconsidered, saying about the TNT, “I was just the one who handed it to the guy who did the job.”

One of her final operations involved funneling misinformation to a Chinese fortune-teller whose radio show was a favorite of Japanese soldiers. She and a colleague drummed up various scenarios: an earthquake in Japan? Too commonplace. Maybe an earthquake and a tidal wave?

They settled on something vague but catastrophic — “something we can’t even mention because it is so dreadful and it is going to eradicate one whole area of Japan.” That same day, Americans dropped the atom bomb on Hiroshima, prompting an astonished colleague to ask how she knew about the top-secret program.

After the war and in need of income, Mrs. McIntosh had a brief, miserable stint covering fashion for Glamour magazine before moving on to writing jobs for the Voice of America and the State Department. From 1958 to 1973, she worked for the CIA on classified operations that often used her burgeoning literary career as a cover.

Under her then-married name of Elizabeth MacDonald, she had written in 1947 a well-received memoir, “Undercover Girl” (1947), which featured an introduction by OSS founder William “Wild Bill” Donovan. In the foreword, he called her “a very effective agent.”

His only objection to the book was that she had described him as “penguin-shaped.”

She later quipped, “Well, he is.”

As Elizabeth Heppner, a later married name, she wrote two children’s books in the late 1950s, “Inki” (later republished as “Inky”) and “Palace Under the Sea.”

Her best-known book remains “Sisterhood of Spies: The Women of the OSS” (1998), which briskly sketched the careers of many of the approximately 4,000 women who served in the agency. Some were code clerks, analysts or secretaries in Washington.

Others volunteered for riskier assignments. Virginia Hall, a wellborn, multilingual Marylander who became known to the Nazis as the Limping Lady because of her artificial leg, helped French Resistance fighters wage guerrilla warfare against the occupying Germans.

She was showered with medals and later joined the CIA, but seemed to some colleagues adrift in the bureaucracy, a generation removed from relevance by the time she was forced into mandatory retirement in 1966.

Another woman of wiles, Amy Thorpe, was a Washington socialite whose seduced an attache at the pro-German embassy of Vichy France to obtain a copy of naval codes that were helpful in planning the Allied invasion of North Africa.

Mrs. McIntosh lectured widely on the role of OSS women and became involved in an alumni group called the OSS Society, serving on its board and as an editor of its journal.

“Betty McIntosh,” said Charles Pinck, president of the OSS Society, “represented the important and unheralded role that women have played in the U.S. intelligence community since its inception.”

Elizabeth Sebree Peet was born March 1, 1915, in Washington, where her father was sports editor for the Washington Herald. Her godfather was Walter “Big Train” Johnson, a vaunted player with the Washington Senators.

After completing high school in Hawaii, she graduated in 1935 from the University of Washington.

Her first marriage, to Alexander MacDonald, a journalist who served in the OSS in Thailand and later started the English-language Bangkok Post newspaper, ended in divorce. After the war she married Richard Heppner, a law colleague of Donovan’s who became deputy assistant secretary of defense for international security; he died in 1958. Her third husband, Frederick B. McIntosh, a former Air Force lieutenant colonel, died in 2004 after 42 years of marriage.

She had no children and leaves no immediate survivors. After being widowed a second time, she had moved to a retirement community in Lake Ridge from Leesburg, Va.

As a young reporter, Mrs. McIntosh covered the Pearl Harbor raid and its aftermath, but she said her editors at the Hono­lulu Star-Bulletin would not run her story because it was too graphic in its description of blood-soaked children and other victims.

The Washington Post’s Outlook section published it in full in 2012 to commemorate the anniversary of the attack.

At her office, she wrote, “there were frantic calls from all sorts of women — housewives, stenographers, debutantes — wanting to know what they could do during the day, when husbands and brothers were away and there was nothing left but to listen to the radio and imagine that all hell had broken out on another part of the island.

“It was then that I realized how important women can be in a war-torn world.”