It was to be the war to end all wars, yet just over 20 years after the First World War ended, Europe was being plunged into a second world war.

It was a war some believed would be contained and over within months, but it killed and wounded 37 million people, soldiers and civilians, in a carnage that lasted four years.

The First World War could be said to have crept up on many in Europe, politicians included.

In the months leading up to it, the political preoccupation in Britain was with Ireland and its move to Home Rule and not events in Eastern Europe.

What happened between 1914 and 1918 did not just alter the world as it was then. It shaped the modern world and its legacies live on - the continuing strife in the Middle East being one example.

In this special section of our RTÉ News site, you can learn a great deal more about the events that led to war in 1914 and their subsequent historical consequences and see, watch and listen to fascinating archive material - including the voices of Irish men who endured the trenches and their horrors.

We have brought together experts such as Professor John Horne of TCD, Editor of the Companion to World War I, and Dr Conor Mulvagh of the Centre for War Studies at UCD.

They have contributed, along with colleagues at RTÉ, a truly enlightening insight into the events of 100 years ago.

RTÉ News Editor Donal Byrne

Survivors of the Somme

Lasting between 1 July and 18 November 1916, The Battle of the Somme was to become one of the defining moments of the First World War. Listen to the Doc on One from 1989 here

The Forgotten War? Ireland and World War I

A discussion about the role thousands of Irish men and women played in the First World War, questioning what made so many citizens sign up to fight with the British army

It Says in the Papers, 7 August 1914

John S Doyle on how the papers reported calls to arms from Kitchener and the Kaiser

Early casualty remembered

Helen Donohue reports on the unveiling of a plaque to honour Joseph P Murphy, one of the first Irishmen to die in WWI

It Says in the Papers, 6 August 1914

John S Doyle reports on the papers' take on the widening war

The lingering hazards of WWI

Donal Byrne reports that even today in both France and Belgium the legacy of the First World War still poses a risk to the health and safety of many people. Those living on or near former battlefields must deal with many problems ranging from unexploded shells to water contamination. 

The Irish in WWI

Watch: Bryan Dobson reports that Irish born soldiers serving in the British Army were involved in fighting in Belgium and France from the very beginning. More than 200,000 Irishmen took part in the war and as many as 36,000 paid with their lives

Irish veterans remembered

Many thousands of Irishmen volunteered to join the British Army, some out of economic desperation, many out of a belief that it would advance the cause of Home Rule. Sinéad Hussey has been looking back at the archives and interviews recorded with veterans of World War One before their deaths.

It Says in the Papers, 5 August 1914

John S Doyle sums up how the papers reported on Britain entering the war

The Great War - Europe Remembers

David McCullagh presents a special programme on the First World War commemoration ceremony in the Belgian city of Liege, marking the centenary of the outbreak of WWI.

Britain Declares War on Germany

Watch: Sinead Hussey reports on the events of 4 August 1914

It Says in the Papers, 4 August 1914

John S Doyle on how the newspapers reported on John Redmond's offer to put the services of the Irish Volunteers at the disposal of the British government for the protection of Irish coast 

It Says in the Papers, 3 August 1914

John S Doyle reports on the newspapers' take on the outbreak of the First World War

Interview: President Michael D Higgins

President Higgins talks to Bryan Dobson about the impact of WWI

Why did the World go to War?

Even historians still cannot agree on how the First World War began, writes Conor Mulvagh of the School of History and Archives at University College Dublin.

Memories of World War I veterans recalled

Listen: Morning Ireland Series Editor Shane McElhatton pays tribute to World War I veterans

Talking World War I

Watch: David McCullagh meets TCD Professor John Horne

My Grandfather's War

Since I was a small child I have always known that my grandfather, John Cassin, served in the First World War, writes RTÉ's Anne Cassin.

My Father's War

Watch: Broadcaster Gay Byrne learns about his father Edward's experiences as a member of the cavalry in the British Army during the First World War

Nationwide Specials

Watch: The Nationwide teams looks at the Irish men that fought in WWI

My Great War

Watch: Young descendants of Irish soldiers travel to Europe to hear the stories of their relatives who fought in the British Army during World War I.

The Forgotten War

A discussion about the role thousands of Irish men and women played in the war, questioning what made so many citizens sign up to fight with the British army.

Gallery: Death and Destruction

World War I left 37 million casualties in its wake, including millions left injured and deformed, and left towns and cities in ruins

Gallery: The War Machine

Industrialisation and mass production of weaponry in the lead-up to World War I made war on a scale never seen before possible

Gallery: Trench Warfare

A selection of images of life in the trenches to mark the centenary of the outbreak of WWI

Gallery: Lights Out

Lights across Britain were switched off for an hour last night in a tribute to the dead of WWI

Franz Ferdinand, Gavrilo Princip and the shots that led to WWI

On 28 June 1914, an event occurred that changed the course of history: the assassination of the heir-apparent to the throne of Austria-Hungary, Archduke Franz-Ferdinand, and his wife, Countess Sophie Chotek.