Secret service documents released on Friday shine new light on the close relations between Irish republicans and Nazi secret agents in the 1940s.
Leading IRA nationalist Frank Ryan became a German collaborator at the start of the one of the world’s most bloody wars, according to archivist Howard Davies.
Ryan had originally travelled to Spain to fight in the civil war there, but landed up in prison when he found himself on the losing side.
While friends were desperately trying to track him down, the Nazis negotiated his release and spirited him away to Berlin.
In Berlin, Ryan met IRA chief-of-staff Sean Russell who had used a steward on an American liner as a go-between to contact the Germans to offer his services as an agent.
Both men were dispatched to Ireland in a U-boat on a mission code-named Operation Taube (Dove).
Russell however died en route and the mission returned to base. One version says ulcers killed him, but a memo in the files suggests Ryan poisoned him because of old political rivalries.
After this escapade, Ryan wanted to return home but he had attracted the attention of Edmund Veesenmayer, a senior official at the German Foreign Ministry.
"Veesenmayer began to groom him for his role as leader of Operation Taube II, the proposed sequel to the Russell mission," according to a report of the interrogation of a top German saboteur.
"[Ryan] was at the same time to approach the Irish government and suggest that the German invasion of Britain would be an opportune moment for the seizure of Northern Ireland"
1940 archive report
Ryan was to use his extensive political, media and trade union contacts in Ireland to stir up opposition to England.
"[Ryan] was at the same time to approach the Irish government and suggest that the German invasion of Britain would be an opportune moment for the seizure of [British-ruled] Northern Ireland," the report continues.
Ryan said he believed Irish prime minister, Eamon de Valera, would back the plan and handed German agents a list of 23 people whom he said would be reliable contacts in Ireland.
They included IRA commanders and Maud Gonne, muse of the poet WB Yeats.
Change in circumstances
But by the winter of 1941, the theatre of war had changed.
With a German invasion of Britain now no longer likely, Taube II needed to be revamped.
German troops were to be on standby in Brest, France, ready to be smuggled into Ireland to stiffen Irish resistance.
The Germans thought Britain might invade Ireland in order to obtain strategic control of southern Irish ports.
"It was Ryan's task to ensure that the Germans would be welcomed as allies and liberators," the report said.
But the plan never came to fruition. Ryan died in February 1944 and was buried under an assumed name in Dresden, leading to decades of controversy about his fate.