TODAY marks the 150th anniversary of Gettysburg. The American Civil War battle saw more than 165,000 Union and Confederate soldiers swarming around the woods and fields of the crossroads Pennsylvania town. When it was over, Gettysburg ranked as one of the most important victories of the war for the North, but it exacted a terrible price. In just three days over 51,000 men had become casualties — many hundreds of them Irish.

The slaughter of the Civil War took place thousands of miles from Ireland’s shores and has remained far from our historical consciousness. However, outside of World War One, the conflagration that engulfed the United States between 1861 and 1865 saw more Irishmen in uniform than at any other time in history. Wartime America was home to over 1.6m people of Irish birth; they accounted for over a quarter of New York’s population alone.

Many of these immigrants had fled an Ireland ravaged by famine, hoping to find a better future for themselves and their families. For thousands these hopes were dashed when war erupted in 1861.

The Irish representation in the armies marching towards Gettysburg in 1863 was not evenly spread.

The majority lived in the industrialised North in New York, Boston and Philadelphia, and as a result most wore Union blue. At least 150,000 Irishmen served in the Yankee ranks, with 20,000 in Confederate grey.

There are no figures as to how many Irishmen died in the Civil War, but it is likely that it ran perilously close to the 35,000 Irish lost during World War One. In a war that killed some 750,000 people, the Battle of Gettysburg is remembered as one of its greatest bloodbaths.

Ethnic Irish units such as the Irish Brigade and 69 Volunteers performed heroics at locations that would become known simply as the ‘Wheatfield’ and ‘Bloody Angle.’ On Jul 3, 1863, the battle reached its zenith, when 12,000 Confederates stepped off to attack the Union line in what became known as ‘Pickett’s Charge.’ Colonel Thomas Smyth, a former farmer from Ballyhooly in Co Cork, was one of the Union soldiers who faced down the desperate charge.

Struck in the face by a shell fragment, he turned to his men saying he was ‘willing to sacrifice my nose for the sake of my country.’ Smyth would survive Gettysburg, but on Apr 9, 1865, he became the last Union general to die in the American Civil War, succumbing to wounds inflicted by a Rebel sharpshooter.

Brothers Patrick and Denis Downing from Skibbereen were also among those who faced the Rebel tide. Both were Fenians and hoped to return to Ireland and fight for Ireland’s freedom. Serving with the New York Infantry, Denis was so severely wounded that his foot was amputated.

So many Fenians died at Gettysburg that Patrick wrote to Fenian leader John O’Mahony from the battlefield to tell him of the Brotherhood’s losses. Pickett’s Charge also impacted another notable Irish nationalist, John Mitchell. The former Young Irelander was a staunch supporter of the Confederacy and his youngest son Willie had been among the dead.

With the Southern retreat from Pennsylvania the process of remembrance began quickly. Only two days after the fighting ended Irishman Timothy O’Sullivan arrived at Gettysburg. He was one of America’s most notable battlefield photographers. The images of the bloated and disfigured brought the war home to thousands of people in a way unimaginable only a year previously. They remain some of the most powerful images recorded in US history.

The Battle of Gettysburg and the American Civil War exacted a terrible toll on the Irish community. Only weeks before the battle Union soldiers donated thousands of dollars for the relief of the starving in Ireland. These were men like Michael Cuddy, Hugh Murphy and Dennis Brady, who despite being in the midst of unspeakable horrors found time to remember those at home. All three died at Gettysburg.

Despite the scale of the Irish sacrifice in the American Civil War, it receives little attention here today. There is no national memorial and there have been no efforts by the State to mark the anniversary. Just as men like Michael Cuddy, Hugh Murphy and Dennis Brady took the time to remember their homeland before giving their lives for the United States, perhaps it is time that Ireland now takes time to remember her 19th century emigrants and one of the most important conflicts in Irish history.

Damian Shiels is author of The Irish in the American Civil War