A fire engine that came from the Irish Republic to help Belfast after the 1941 Blitz has gone on display in the city.
The vehicle, which arrived on Wednesday, was one of 13 Irish engines that responded to an emergency request from Northern Irish authorities following the first attack on Belfast by German bombers.
On the night of Easter Tuesday, 1941, around 180 German planes dropped 200 tonnes of high explosives on Belfast, and fires from 29,000 incendiary bombs ravaged the city.
Almost 1,000 people were killed and 100,000 left homeless in the attack.
With their already insufficient resources stretched to breaking point, the Northern Irish government sent a formal request for assistance to Dublin on the morning of Wednesday 16 April 1941.
Eamonn de Valera, the taoiseach (Irish prime minister) at the time, was put in a very difficult position by the request. Ireland was supposed to be neutral, and there was a very real fear that any breach of this neutrality could lead to a German invasion.
Only the previous year Nazi Germany had invaded Belgium, the Netherlands and Norway: all of them neutral countries.
When De Valera was awoken in the early hours of the morning by an urgent telegram from Belfast, he therefore faced an extremely risky decision.
However, within two hours of receiving the request, at least 70 men and 13 fire engines were on their way north from Dundalk, Drogheda, Dublin and Dun Laoghaire. Each man was a volunteer.
In a highly significant gesture of cross-border cooperation, traditional hostilities, and even Ireland's cherished neutrality, were put on hold in the face of a humanitarian tragedy.
This was not the first time the Irish Republic adopted a stance of what historians have termed "benevolent neutrality" towards the UK.
The controversial Donegal Air Corridor, which allowed Allied planes access to the Atlantic Ocean from their base in County Fermanagh, was negotiated earlier the same year.
It was however a unique and poignant example of north-south partnership. It was the first time, albeit briefly, that Ireland became actively involved in the Allied war effort.
Afterwards, long-standing Fianna Fail cabinet minister Frank Aiken summed up the simplicity of the decision to the American press: "They are Irish people too," he said.
Eamonn O'Cuiv, a member of the Irish Parliament for Fianna Fail and Eamonn de Valera's grandson, has called for a memorial to the firemen who answered Northern Ireland's call for help.
Praising the courage of the volunteers, he said there should be a joint north-south recognition to honour their actions.
"Maybe there should be a permanent memorial, commemorating what was, in a difficult time, one of the important north-south gestures," he said.
Mr O'Cuiv was speaking in an RTE Radio 1 documentary, Hidden Heroes, which investigates De Valera's crucial decision and the actions of the firemen.
Among the revelations in the programme is the fact that there is no record of all of the firemen's names, and that the order book of the Dublin Fire Brigade omits any reference to their mission.
Scant details were recorded by the fire brigades in Dun Laoghaire, Drogheda and Dundalk.
"I am sure part of the reason was to mollify any question the Germans might raise about it," said Mr O'Cuiv.
"The Germans could have taken the view that it was a violation of neutrality. But (De Valera) weighed up the risk and decided very, very quickly that there were people on the island of Ireland, Irish people, who needed help."
The programme goes out on RTE Radio 1 on Saturday 16 April at 1805 BST. It is presented by Paddy O'Flaherty, grandson of Patrick Rooney, who was the driver that fateful night of the fire engine now on display at Belfast City Hall.
The fire engine is on display as part of the Belfast Blitz exhibition, commissioned by Belfast City Council to commemorate the 70th anniversary of the attacks.