Their motivations were often the same as those who joined up in England, Scotland and Wales: a sense of duty, the belief that the war was a just cause, a desire for adventure, the bonds of friendship and economic reasons.
They volunteered for adventure. They volunteered to see the world even one torn by war. They volunteered for the better good. They volunteered because their friends did.
Different social classes joined the military for various reasons, including the Anglo-Irish officers who thoroughly wished to support the "mother country", while others, typically poorer Irish Catholics, did so to support their families or seeking adventure.
Over 200,000 men from the island of Ireland served in the British military during the First World War. Around 35,000 lost their lives. Those who returned found that commemoration of their service was controversial in a way that it was not in Britain.
After the outbreak of war in August 1914, Britain recruited a huge volunteer citizens' army. In just eight weeks, over three-quarters of a million men in Britain had joined up. Every volunteer had to undergo a series of medical and fitness tests before being accepted as a soldier.
Lord Derby, a politician, encouraged men to join up with their friends as a way to recruit more soldiers. People who already knew each other would be good for the army. They would keep each others' spirits up. These groups became known as 'Pals Battalions'.
On 27 December 1914, Casement signed an agreement in Berlin, authorizing the brigade, with German Secretary of State Arthur Zimmermann. Only 56 Irishmen volunteered and they were brought together at a POW camp at Limburg an der Lahn.
These men were shunned, ostracised from Irish society and in many cases murdered by the IRA, but that is only part of the story. Some 210,000 Irishmen served in the British Army in the first World War. There were simply too many for them to be ignored.
One of the effects of the heavy casualties of 1916-17 as well as sluggish recruitment in Ireland itself, was that the Irish Divisions began to lose their distinctive Irish character as losses were often replaced with new recruits or conscripts from England.
During World War I (1914–1918), Ireland was part of the United Kingdom of Great Britain and Ireland, which entered the war in August 1914 as one of the Entente Powers, along with France and Russia.
Ireland was part of the United Kingdom from 1801 to 1922. For almost all of this period, the island was governed by the UK Parliament in London through its Dublin Castle administration in Ireland.
Many Irish worried that radicalism on both sides of the slavery issue would wreck the Republic. The attack on the American flag at Fort Sumter by the Confederates took a peaceful resolution of the sectional crisis off the table. The Irish project of maintaining the “Union as it was,” was forever dead.
The British Government ordered the deployment of troops to Northern Ireland in August 1969. This was to counter the growing disorder surrounding civil rights protests and an increase in sectarian violence during the traditional Protestant marching season.
De Valera stated in his wartime speeches that small states should stay out of the conflicts of big powers; hence Ireland's policy was officially "neutral", and the country did not publicly declare its support for either side.
In 1914, the Indian Army was one of the two largest volunteer armies in the world; it had a total strength of 240,000 men while the British Army had a strength of 247,433 regular volunteers at the outbreak of the war.
Initially, Australian men volunteered to enlist for different reasons, because they: needed regular pay. sought combat or adventure. wanted to escape from normal life.
One modern estimate estimated that at least 200,000 were killed out of a population of allegedly 2 million.
In July 1917, Eamonn de Valera became the President of Sinn Fein. He had taken part in the Easter Rising, but had not been executed. He stood in the Clare East by-election, openly declaring his belief in an Independent Irish Republic.
Video: 1916 – The War at Home and Abroad
In Ireland, the majority was supportive of the war effort, with many Irish divisions placed across Europe. Yet a small but significant minority were interested in a struggle closer to home as was proven on Monday, 24 April, when the Easter Rising began.
“An investigation is underway and a report on the incident will be submitted to a local court. “We can't comment on the possible causes at this stage.” A spokesman for the Defence Forces said: “We can confirm that a serving member has died in a parachuting accident in Spain. He was off duty at the time.”
Ireland did not join the war, but declared neutrality. Indeed the world war, in Ireland, was not referred to as a war at all, but as 'The Emergency'. In staying neutral, despite British and latterly American pleas to join the war, Ireland, under Eamon de Valera, successfully asserted the independence of the new state.
Most of the Irish soldiers fought in Flanders and thousands perished in the First and Second Battles of Ypres. These casualties are buried in the Cemetery at Messines. After the war, the British Commander in Ypres, Sir John French, became the Governor General of Ireland.
In 1169, a group of Norman soldiers and knights arrived in Wexford to help the Irish king of Leinster, Diarmuid MacMurrough. They were invited by Diarmuid to help him fight his enemies and regain his kingdom in Leinster.
In the final months of 1922, Terence Brady, Leo Dowling, Sylvester Heaney, Anthony O'Reilly and Laurence Sheeky were stationed on guard duty at Baldonnell Airfield.
The Irish War of Independence, or Anglo-Irish War, was the climax of a centuries-long struggle for control of Ireland that had seen many bloody wars and revolts against English (and then British) rule, including the Rebellion of 1798.