In her book of memoirs, published in 1972, which I just read, Maria [she assumed Marya] von Heimburg Mannes tells us that she was in Lisbon during WW2 for intelligence gathering purposes, on behalf of the Counter-Intelligence Dept. of the American OSS, which had approached her in the winter of 1943. Her code name was [or could be, because she gives no assurance about it] agent B548.
She arrived in the Tagus River, by clipper, on 3 June 1944. She would return in September of the same year. Her cover was that she was working for The New Yorker magazine.
During the flight she met George Kennan, who was finishing his term as US Chargé d’Affaires in Portugal and briefed her extensively about the situation in this country, telling her «more than I had learned from prior briefings». Another passenger – whose name she does not reveal – was «the director of an international business cartel based in Lisbon who was later to be of help in many ways, some of which we would not know».
Following instructions, she travelled to Madrid also.
Some of her findings were published in The New Yorker magazine that summer [read about them in Malomil blog, here]; her last act as a journalist was to send a requested article to Vogue about fashion in Lisbon.
The daughter of a well-known musician and composer, David Mannes [see his autobiography here], Marya – whose personality, even as regards her sentimental side, is fascinating – lived a full life between literature, theatre, music, and writing for periodicals, mostly on fashion and social events.
Marya’s duty was to gather information about German penetration in Portugal, infiltrating Axis circles and ranks of Portuguese sympathizers.
According to David Waller [on his biography of Bill Donovan], she was even raped by a Portuguese manufacturer of parachutes for the Germans. But according to her own account of the incident no physical contact occurred.
In Madrid, she met a man who would later be compromised as an Abwehr agent, Paul Jean Marie Cavaillez. She kept a long relationship with him, even later, when back in America.