A group from County Kerry, Ireland, marches up Fifth Avenue during the St. Patrick’s Day Parade in New York. The 2016 parade marks the centennial of Ireland’s Easter Rising against British rule. (Mary Altaffer/AP)

Today, Irish people are commemorating the 1916 Easter Rising, the failed rebellion that led a few years later to Irish independence. Here’s what you need to know about it.

Why did the Rising happen?

The Rising was the result of a resurgence of Irish nationalism in the late 19th and early 20th century. Cultural organizations such as the Gaelic Athletic Association (which promoted Irish sports such as hurling and Gaelic football) and the Gaelic League (which pushed the revival of the Irish language) helped generate a new sense of shared identity. This led to increased pressure for Home Rule (a limited form of independence) among moderate nationalists and complete independence among radicals. By 1913, Northern Unionists who opposed Irish nationalism were mobilizing against proposals for Home Rule, setting up an armed organization called the Ulster Volunteer Force.

This led Irish nationalists to set up their own organization, the Irish Volunteers in 1913, which was nominally led by my great-grandfather, Eoin MacNeill. This organization soon split over disagreements about whether Irish men should volunteer to fight in World War I, and the remnant of the organization became dominated by the Irish Republican Brotherhood (IRB), a radical group that wanted complete independence, if necessary through armed insurrection.

The IRB, together with the Irish Citizen Army, a much smaller left-wing organization, decided that the time was right to strike against Britain. Without informing MacNeill and other leaders, they decided to mobilize the organization across the country for an armed rebellion on Easter Sunday 1916. MacNeill, who heard about the rebellion at the last moment, issued a countermanding order that was published in a national newspaper. The result was that very little happened outside Dublin.

How did the Rising unfold?

Bloodily. The leader of the Rising, Patrick Pearse, was more inspired by general notions of blood sacrifice than specific military tactics and strategy. The rebellion had little to no chance of succeeding on its own terms. It succeeded in taking some prominent buildings for a short period and turning Dublin’s city center into a war zone. However, as soon as the British mustered a counterattack (in particular, by sailing a gunboat up Dublin’s main river to bombard the rebels and unfortunate civilians), the rebellion crumpled and the key leaders were quickly rounded up.

Even if the rebellion was botched, it provided a number of young militants with a swift introduction to the principles of warfare, which they put to great effect during the Irish War of Independence a couple of years later (while deliberately avoiding symbolic set-piece battles such as the Rising, where they would be militarily disadvantaged).

The Rising failed, so why is it important?

The British reaction to the Rising radicalized Irish public opinion. British Maj. Gen. John Maxwell (who came to be known as ‘Bloody Maxwell’) set up an effective regime of martial law in Ireland, mounting thousands of raids and swiftly executing 15 of the rebels (including Pearse’s younger brother, who had not had significant leadership responsibilities). Two more were executed a couple of weeks later, despite explicit instructions from Britain’s prime minister to halt the executions (one of the men executed, James Connolly, had to be shot while seated in a chair, because he was too badly wounded to stand up).

This inflamed the Irish public, including moderate nationalists who might otherwise have been inclined to condemn the rebellion. It set the stage for a much wider and more intelligently fought revolt, in which Irish militants turned to guerrilla tactics, using tacit public support and the rugged Irish countryside to their advantage by attacking isolated groups of police and military, and then melting away. Michael Collins, one of the Easter rebels, developed a genius for hit-and-run tactics, reputedly influencing later practitioners of guerrilla warfare such as Mao Zedong and Yitzhak Shamir.

What are the consequences of the Easter Rising today?

The Easter Rising’s political legacy is contested and complicated. After Irish rebels achieved independence, they split over the question of whether to accept a compromise in which Britain retained control over Northern Ireland, fighting a civil war. The losers in that civil war gave birth to the Irish Republican Army (IRA), which considered itself for a long time to be the true heir of the independence movement and which saw the Easter Rising as an inspiration. For a long time, the Irish state and the militant republican movement fought over the meaning of the Easter Rising, each trying to use the events to legitimate itself.

The result is that the Irish state has sponsored a series of events intended to commemorate the Easter Rising, but also to acknowledge its complexities, and to acknowledge aspects of the Rising that were previously underplayed (such as, for example, the important role of women). However, police and politicians in both the Republic of Ireland and Northern Ireland fear that dissident Irish republicans might use the anniversary of the Easter Rising to stage a terrorist attack, claiming that they are continuing the tradition of militant Irish republicanism.

Where can you find out more about the Easter Rising

There are two excellent recent books covering the Rising. Diarmuid Ferriter’s “A Nation and Not a Rabble” provides a fine overview of the Rising, its consequences for the Irish independence movement, and how historians and nationalists thought about it after it had happened. Roy Foster’s “Vivid Faces: The Revolutionary Generation in Ireland” looks at the young people who were involved in the upsurge of nationalism and cultural activity that led to the rising. Colm Toibin, who wrote the novel behind last year’s Academy Award-nominated film “Brooklyn,” has a superb essay on the Rising in the London Review of Books. My sister Maria Farrell has a shorter piece on Eoin MacNeill and the historical legacy of the Rising here.