When the Luftwaffe bombed Dublin on May 30th, 1941, killing 34 civilians and wounding another 90, the German minister in Dublin, Eduard Hempel, went straight to the Department of Foreign Affairs to ask its secretary, Joseph Walshe, what had happened. He suspected the British had dropped the bombs to force what was then called Eire into the second World War.
Frank Aiken, then minister for co-ordination of defensive measures, told me years later: "Of course, we knew it was the Germans". The bomb fragments were found to carry German markings; Berlin, anxious to make amends, broadcast Ireland's complaint to Germany over Axis radio stations.
An intriguing series of reports in the military archives in Dublin, however, suggest that only two nights earlier the Luftwaffe had almost attacked Dublin in error and that several German aircraft had dropped their bombs off the east coast when they discovered their mistake at the last moment. If the British had interfered with their radio beam, this could account for the German pilots' error on the night of May 28th and their actual bombing of North Strand Road two nights later.
According to the Irish Air and Marine intelligence file for May 28th, 1941, 50 aircraft, reported as "unidentified" but almost certainly German, flew across the south-east coast of Ireland just after midnight, heading north.
An Air Corps mapping officer noted: "It would seem that large waves of aircraft flying in flights [sic] entered the country at three main points 1) Carnsore and Cahore 2) Kilmichael and Wicklow and 3) the Browns town to Carnsore area . . ." The planes were heading for Dublin.
Some flew up the Wicklow coast, passed over Dalkey and flew on towards Rush. Another reached Cootehill, then turned round, while another was heard over Mountmellick. A strong force of heavy aircraft had clearly become confused when the land below them no longer matched their bomb-aimers' maps. Explosions were heard over the sea off the coast, probably the Luftwaffe ditching their bombs, before the sound of aircraft faded away. Two nights later the Luftwaffe returned and bombed Dublin.
Neither British nor Irish records prove that the British government bent the German radio "beam" to lure Luftwaffe bombers away from Britain and towards Dublin. Indeed, the British did not "bend" the German beams at all; they "smothered" the German radio navigation signals - two intersecting lines used to guide the bombers - in such a way that the aircraft would begin to wander around the sky looking for the genuine signals.
This would produce exactly the pattern of events recorded by the Air Corps on May 28th, which may well have involved Luftwaffe aircraft originally charged with bombing Cardiff, Swansea or Milford Haven. Is this what happened again on May 30th when they did bomb Dublin, or was it, as some have suggested, a deliberate attempt by the Germans to punish de Valera for sending his "neutral" fire engines to fight the fires in Belfast after the earlier German blitz on Northern Ireland?
Three weeks earlier, the English-language service of German radio had commented on Britain's need for the three Treaty ports (Cobh, Berehaven and Lough Swilly) and made the odd remark: "It is conceivable that, to gain their ends, the British intend to bomb Eire and then declare that this crime was committed by Germany".
Was there foreknowledge in all this? Or, more likely, was the Luftwaffe simply turned away from its original targets by the British? Since the British could not actually "bend" the beam, it is unlikely they would have been able to send the Luftwaffe towards neutral Ireland, but since they could obscure the German radio navigation signals, they would certainly not have been unduly upset if the bombing of neutral Dublin had been the result.
Robert Fisk of the London Independent wrote In Time of War: Ireland, Ulster and the Price of Neutrality, 1939-1945, published by Gill and Macmillan