Shaking off her shoes while leaving her jacket on her seat, Zo padded out of her train compartment and edged her way down the corridor. Glancing back, she saw the pale face of the man who had been following her lean out to watch. ‘Shit’, she thought, pressing on. It was May 1942, and Zo was both an intelligence officer and a courier for the Polish ‘Home Army’, one of the largest national resistance forces of the war. She had been trying to lose her tail ever since she had returned from her latest clandestine trip to Berlin. There, traveling on Polish-forged papers as a German oil company secretary, she had delivered microfilm of military intelligence to a trusted member of staff at the Manchurian embassy. He then forwarded her ‘mail’ to London, in the diplomatic post. In exchange, he had handed her a block of dollars to smuggle back to the resistance in Warsaw.

Once across the border in Poland, Zo had managed to safely stow the money before she had somehow attracted the attention of the German occupying authority’s security men. But her head was full of the names and addresses of resisters, safehouses and contact points. Terrified that brutal interrogation might make her betray her colleagues, she decided she could not let herself be caught alive.

The train raced on. It was night, but through the corridor windows Zo could see telegraph poles whizzing past in the darkness. The next station was still several miles away. Pausing as she reached the passenger door, she looked the guard straight in the eye. ‘I am from the Home Army’, she told him steadily. ‘Get the door, I’m going to jump.’ Wordlessly dropping his hand to the lock, the guard lent in and pushed the door wide. At this moment of ‘mortal danger’, Zo later recalled, she thought of ‘cowboy literature, of which I was very fond.’ The thought occurred to her that, ‘these chaps jump upwards into the air to slow down their momentum.’ And so, she leapt up. Then she fell down. Hard. Landing on gravel, she grazed her arms and knees, but she had not been smashed through by a telegraph pole or crushed beneath the steel wheels of the train, and she had, once again, evaded arrest.

In late May 1945, a report commissioned by Winston Churchill revealed that almost half of Britain’s wartime military intelligence in the European theatre had come from Polish sources. Poland, whose invasion by Nazi German forces on 1 September 1939 had triggered the Second World War, had put up a better defence than is often remembered. On 17 September, however, the country had faced a second invasion. As the Soviet ‘Red Army’ crossed Poland’s eastern border, ostensibly to protect the ethnic Russian population but in fact under the terms of a secret protocol with Germany, the Poles knew they could not keep fighting effectively on two fronts. Instead, the government, treasury, 35,000 troops, and the country’s pioneering team of enigma experts, evacuated to Romania and regrouped in France to continue the fight. Those who remained, men and women, quickly formed the fledging Polish resistance; various independent clandestine groups came together as the Polish ‘Home Army’.

Having sworn her resistance oath in a cold Warsaw kitchen before 1939 was out, Zo – in fact Elżbieta Zawacka, a leading member of the pre-war Polish Women’s Military Auxiliary – had immediately proposed organising her friends into an intelligence-gathering network. She focused her efforts on women partly because so many men had already left the country, but mainly for their gender-specific superpower: women’s greater ability to be overlooked and underestimated. Zo had spent years petitioning the Polish authorities for formal recognition of the women’s military auxiliary to no avail. Now she delighted in exploiting the initial security lacuna created by the misogyny of the Third Reich. Yet Polish women were never entirely exempt from enemy attention, and when German soldiers started to realise what Zo and her colleagues, the laughing girls in cafés and old ladies sitting on trams, were up to, their response was invariably brutal.

Within a month, Zo had recruited fifty women. Within six months, there were 200, including an intelligence officer in every town across Silesia, an area around the size of Wales. The priority was military reconnaissance. Each officer produced weekly reports on enemy troop numbers, deployment and morale, using statistics collected by women working in post offices and telephone exchanges who steamed open letters and eavesdropped on conversations, and by translators, secretaries and office cleaners who memorised maps and paperwork in the bureaus of the occupational authorities. Women who took in washing noted the number and type of uniforms passing through, bakery workers recorded changing garrison orders, and barmaids risked opprobrium to chat with the enemy and report back on military gossip. Most valuable of all were the women whose homes or places of work overlooked military installations, police stations, railway tracks or the main thoroughfares, enabling them to count the number and direction of troop trains and military freight.

None of this intelligence had value, however, unless it reached the Home Army’s headquarters. Once again, Zo had volunteered, this time to serve as the main courier for her network, a thin paper aid-mémoire hidden alternately in the back of her clothes brush, slipped into the cover of a prayerbook, or stuffed inside a loaf of bread. As the resistance grew more sophisticated, with film and forgery departments, she had started smuggling microfilm hidden within the shaft of a door key.

Zo had been born in Toruń, in 1909, in what is now north-western Poland. Although historic Polish territory, the region had then been annexed into the Prussian Empire. As both Polish language and heritage were suppressed, Zo grew up speaking German. Outside her home, she was even known by the German version of her name, ‘Liza’. Ironically, the authorities were raising her to be a perfect secret agent, bilingual, and accustomed to leading a double life. She was eleven when Poland was restored to the map of Europe, and thirty and in uniform in 1939 when war saw her nation once more divided between its aggressive neighbours. Although highly effective as an intelligence officer and local courier, with her language skills and conveniently blond hair and blue eyes, it was not long before Zo had been deployed to serve on the most perilous route of all – between Warsaw and Berlin. By mid 1941 she had crossed wartime borders over one hundred times but, despite many close shaves, it was another year before she was forced to evade arrest by throwing herself from the moving train.

Although she always travelled on false papers, Zo now knew that her face was known and she could not keep working the same routes. Yet her skills and experience were too good to waste. In late 1942 she was appointed as the Home Army’s only female emissary, charged with crossing almost 1,000 miles of enemy-occupied Europe, from Warsaw to London, carrying microfilm with information too sensitive to be transmitted via radio, and with two missions to undertake in Britain as the personal representative of the Home Army’s Commander-in-Chief.

Zo’s journey would take her back through Berlin, across the border near Strasbourg and on to Paris, where her papers were kept overnight by the military authorities as possible forgeries, but then released. From there she crossed the demarcation line into southern, Vichy, France, balancing on two planks wedged inside the water tender of the steam train designated to Pierre Laval, the collaborationist Prime Minister of France. After several false starts attempting to cross into Spain, one of which saw her being thrown from a hotel window, she hiked over the freezing mountain passes of the Pyrenees with a local guide, at one point being shot at by a German border patrol. She reached Liverpool by troopship from Gibraltar on May Day 1943, with her microfilms still hidden inside a key and a brass cigarette lighter.

‘She was rather reluctant to pass… information on to me’, Zo’s interrogating officer from MI6 noted feebly when she was questioned on arrival in London. Zo was determined that her first debrief would be with her compatriots, exiled in London since the fall of France. The intelligence she had brought included details of German troop movements across Europe and U-boats in the Baltic. There were reports on enemy aircraft, including the pioneering V1 ‘buzz bomb’ and V2 rocket, as well as an overview of German industry and munitions factories with sabotage both planned and undertaken. In addition, there was information on the ghettoes in Poland, Auschwitz extermination camp, and a broader picture of Nazi Holocaust plans. When shared with the British, the head of the Special Operations Executive (SOE) Balkans region was so impressed, he proposed her for ‘some such decoration as the OBE’.

Zo spent three months in London meeting with everyone from General Sikorski, the Polish PM and Commander-in-Chief, down. As well as her intelligence haul, she sorted out problems with the London end of the land communication system and, among her most important work, drafted a decree to give female fighters in the Home Army legal military status as soldiers, and with this some level of protection under the Geneva Convention. She also briefed the Polish special forces, the Cichociemni or ‘Silent Unseen’, on conditions in enemy-occupied territory, before joining them as the only female member of this elite unit.

In September 1943, Zo became the only woman to parachute from Britain to German-occupied Poland. She would go on to play a key role in the Warsaw Uprising, the largest organised act of defiance in Europe. Launched on 1 August 1944, a month after D-Day, and as the Soviets were pushing forward on the Eastern Front, the Polish aim was to drive the Germans from their capital before the Red Army arrived. They knew the strategic importance of welcoming the Soviets as equals and allies, rather than being beholden to them for their liberation.

After two months of brutal battle, during which the Red Army reached, and encamped on, the far side of the city and Stalin thwarted much aerial support from the west, the Poles were forced to capitulate. Just before doing so, their Commander signed Zo’s draft legal decree into force. Because the female combatants were now recognised as soldiers of an Allied army, this was the only time in the war when Nazi Germany established POW camps for female units. Zo’s work saved many thousands of lives, but she refused to be taken prisoner herself. Slipping away among Warsaw’s civilian refugees, she would undertake one more wartime mission.

Zo was finally demobilised as one of the most highly decorated women in Polish history, but she would not receive any of her medals for almost forty years. While Britain celebrated VE Day with bunting and street parties, the Soviet Union was already imposing a communist puppet government on Poland. One of the first acts of this regime was to round up Polish wartime resistance leaders and execute several thousand of them. Zo had narrowly evaded capture many times during the war. Ironically, she would be arrested by her own government in 1951 and sentenced to ten years in prison.

It was only after Poland regained its democratic freedom, in 1991, that her remarkable service as an intelligence officer, courier, emissary, member of the Silent Unseen, combatant in the Warsaw Uprising, and Home Army soldier, was finally recognised. Not only did President Lech Wałęsa present her with Poland’s highest honour, the Order of the White Eagle, he also – which meant much more to her – promoted her to Brigadier General (retired). General Zo remains only the second woman in Polish history to receive the rank.