A Belfast family took part in the Rising and the Somme
The Easter Rising and the Battle of the Somme were both historic events in 1916.
The Somme became a symbol of sacrifice for the British Army. Thousands died in the first day of the battle in July.
It came mere weeks after republicans had launched an ill-fated military strike against British rule in Ireland, known as the Easter Rising.
For one Belfast family, who found themselves on opposing sides of history, the Somme and the Rising were intensely personal.
The Corr family was from the Ormeau Road in the south of the city.
In 1915, influenced by an elder brother Henry, and in their own words, "disgusted at the pro-British sentiment in Belfast", sisters Elizabeth and Nell joined Cumann na mBan, the women's equivalent of the Irish Volunteers.
To Dublin on Easter Saturday
James Connolly was one of the leaders of the 1916 Rising. It was his daughter Nora who led the Corr sisters - and several other women - to take the train to Dublin to join the Rising.
They travelled alone because the men - the Irish Volunteers - who had gathered in Coalisland, County Tyrone, awaiting instruction of when to travel to Dublin, were demobilised.
But the women did not turn back - they made their way to Liberty Hall which has been described as the birthplace of the Easter Rising.
Once there, they met the leaders of the Irish Citizen Army (ICA). It had been set up a few years previously during labour disputes in Dublin and more than two hundred members of the ICA fought in the Rising.
The sisters ran dispatches around the city for ICA, and slept at the house of Countess Markiewicz - an aristocrat who played a key role in the Rising.
Elizabeth Corr's eyewitness account of their experience paints a vivid picture of the hours and days leading up to the Rising:
"Liberty Hall was humming when we arrived. Joseph Plunkett was there, looking very ill with his throat bandaged, and his fiancée (Grace Gifford); Madame, in great spirits; members of the Dublin and Glasgow Cumann na mBan, Mrs Connolly and her son, Roddy.
"Thomas McDonagh (another leader of the Rising) came in, looking very gay and debonair in his spick-and-span uniform, and very different from the very much perturbed man we had met on Sunday morning.
"James Connolly came from another part of the building, and said smilingly, 'Well, girls, we start operations at noon today. This is the Proclamation of the Republic'.
"It was still wet from the press, and we all read it with wildly beating hearts," she wrote.
Taking dispatches north
The sisters left Dublin before fighting began, on the morning of Easter Monday, to bring dispatches north. They were awarded military pensions for the role they played in the rebellion against British rule.
However, hundreds of miles away, across Europe, two of their brothers were fighting for the British Empire.
George Corr was killed fighting for the Australian army, the 54th Australian Infantry Battalion. He died during the Battle of the Somme in July 1916 - he was 34 years old.
His brother, Charles, fought for the Canadian Expeditionary Force. He was gassed on the Western Front several times, but survived and returned to Canada.
The family is now the subject of a new exhibition at the Linen Hall Library in Belfast.
Their great-nephew, Gerard May, said it was only relatively recently that the stories of what happened to George and Charles had become clear.
He said that while their story may sound extraordinary, it was not unique in pre-partition Ireland.
"It's an interesting situation, and one I think our society is only beginning to come to terms with.
"As a family, we will remember them all, the whole of the Corr family.
Respect and honour
"Now that we know more or less a complete story of what happened to them, we will respect and honour them, particularly this year," he said.
It is difficult to tell what impact this had on relations within the family - there are no letters or notes containing any references to strife amongst the siblings, for example. In fact, even decades later it was rarely mentioned, and perhaps that in itself is telling.
"There wasn't a lot of conversation about it," said Gerard May.
Talking about the brothers who fought for the British, he said: "Growing up, we didn't really appreciate too much about it. It wasn't talked about. We didn't really know anything about them until uncle Jack, my father's younger brother died."
Mr May became the first member of the family to visit George Corr's grave in France in 1997.
The Corr Family - Witnessing History exhibition runs at the Linen Hall Library in Belfast from 5 - 30 April.
You can see Catherine's report on BBC Newsline, BBC One Northern Ireland at 1830 GMT.