Operation Kathleen

The Irish decision to remain neutral during the war was only natural; it was the only way for the country to survive. It was by no means able to resist any kind of an invasion, as its army had been neglected after the Civil War, and the experience of the Netherlands and Belgium in 1940 showed that even neutral countries were not safe from German aggression.

Hitler had shown an early interest in Ireland as being a tactically valuable position against Britain and tried to make Ireland join an alliance against Britain. He not only offered military help to improve the Irish army against a possible British invasion, but also suggested to help to solve the problem of Irish partition in return, as soon as the United Kingdom would be defeated.

The German invasion of the Lowlands in May 1940 proved to be a strain on the relations with Ireland. It proved to de Valera and other neutral statesmen that neutrality did not stop the German armies.In 1941 Hitler even argued that "a neutral Irish Free State is of greater value to us than a hostile Ireland", but nevertheless earlier that year he also made General Kurt Student work out an invasion plan for Northern Ireland. Student's plan was to land 32,000 paratroopers and airborne troops by night in two areas; while the larger force would land north of Belfast, capturing RAF airfields at Aldergrove, Langford Lodge and Nutts Corner, the other group would be dropped near Lisburn, to destroy the planes at Long Kesh and to cut the rail connection between Belfast and the south. The next morning, Luftwaffe planes from Brittany would land on the captured airfields. But this plan was eventually abandoned for the sake of other airborne invasions, like the one on Crete.

Another heavy strain on the diplomatic relations between Dublin and Berlin was the 'Goertz-Affair'. Following a police raid on the Dublin home of Stephen Karl Held, member of the IRA and adopted son of a German father, on the 22 May 1940, the police found unmistakable evidence for the earlier presence of a German spy, Hermann Goertz. The seized equipment, included a radio transmitter and receiver, a file containing information about Irish airfields, harbours and other targets, the distribution of the Irish defence forces and the crude outline of a German plan to invade Northern Ireland with the support of the IRA from the south. It was the so-called 'Plan Kathleen' that had earlier been brought to Germany by Held himself, but it was so ludicrous that the German intelligence agency turned it down right away.

An attempt to strengthen the IRA again was the German plan to return the IRA leaders Sean Russell and Frank Ryan, who had been political opponents, to Ireland. At the time of the raid in January 1940, Russell had been on a campaign to raise money in the United States of America, and now he asked the Abwehr to help him return to Ireland, an appeal that delighted the German intelligence, providing it with yet another access to the IRA. The Abwehr managed to get Russell out of the USA and a plan was made for him to return to Ireland, called 'Operation Dove'. After his return on a U-boat the IRA leader would be given free hand in his actions, and he would figure out if joint activities with the Germans were possible. But the whole operation ended tragically, as Russell died on the voyage to Ireland, just in sight of his destination, without telling Ryan about his plans. Ryan therefore decided to return to Germany, where he eventually died in 1944.

..after 1941 Germany was more interested in keeping Ireland neutral than to see it enter the war on the side of Britain. But nevertheless, Berlin tried to achieve at least a positive neutrality for itself and offered the Irish the British weapons left behind at Dunkirk.

On 12th November 1939, eight months before Neville Chamberlain announced that the UK was at war with Hitler's Germany, the IRA under the leadership of Sean Russell issued an ultimatum to the British Government demanding a statement of intent to withdraw from Northern Ireland within four days. When no response was forthcoming, the IRA - the supposed inheritors of the true Republic - declared war on England. By July, 127 explosions had been recorded in Great Britain. Seven innocent civilians died in a campaign almost certainly planned with Nazi connivance, five in one outrage in Coventry.

In 1940 Russell travelled to Germany to try to interest the Reich in a bizarre plan to jointly invade Northern Ireland, codenamed 'Operation Kathleen'. The Germans were not impressed with the IRA, one intelligence officer in Ireland regarding them as "worthless". Russell died of a perforated ulcer on board a German U-boat.

An additional source

=========

Wikipedia