Eighty years ago soldiers from across Ireland were bracing themselves for D-Day.

By air and by sea they joined the 150,000-strong Allied advance on France in June 1944.

After years of aerial bombing raids, rations and hard factory work at home, the mission of Operation Overlord was to seize a foothold in France and turn the tide of the war against Nazi Germany.

In Northern Ireland, conscription was not imposed due to its political divisions, however, citizens from both unionist and nationalist backgrounds signed up for the war effort.

In the Irish Free State, which adopted a policy of neutrality, some 70,000 soldiers would join the British Army as it added Normandy to its other frontlines in Italy and north Africa.

For months, the Allies planned how they would re-enter Nazi-occupied France, four years after the evacuation from Dunkirk.

Under tight secrecy and to surprise Germany, Normandy was chosen rather than the shorter crossing point at Calais.

Shortly after midnight on 6 June 1944, a small number of troops landed on gliders with the mission of seizing key locations such as bridges over the Caen Canal and River Orne.

They were to be relieved by the world’s largest amphibious invasion force which reached Normandy’s beaches from 06:30.

The US 1st Army was tasked with attacking the Utah and Omaha assault zones to the west.

To the east, British and Canadian forces focused on Gold, Juno and Sword.

About 12,000 Allied aircraft and several thousand sea vessels formed part of Operation Overlord.

Met by mortar shells, machine gun fire and snipers, the Allied objective was to breach the enemy’s coastal defences and push towards key cities such as Bayeux and Caen.

The eventual aim would be the liberation of France.

More than 4,000 allied troops were killed on D-Day and thousands of others were wounded.

The Royal Ulster Rifles (RUR) was the only British regiment to have its full strength of two battalions deployed on D-Day.

Many soldiers from the Ireland and Great Britain would also form part of its ranks.

At midday, a few hours after the initial wave of the invasion on 6 June 1944, 2nd Battalion RUR landed at Queen Red beach, part of the Sword assault zone.

Their aim was to advance inland towards a battle for the city of Caen.

The battalion’s war diary states some of the soldiers were small in size and had difficulty getting ashore from the landing craft, carrying equipment, weapons and a fold-up bicycle – although many of those were thrown overboard to be recovered later.

There were some initial casualties due to mortar and shell fire.

However, there were no beach fatalities for the RUR and the war diary states they were met by the sight of surrendering German soldiers.

The 2nd Battalion’s initial objective was to assemble at nearby Lion-sur-mer and they dug in for the night at Périers-sur-le-dan.

The 1st (Airborne) Battalion of the RUR meanwhile was preparing to land by Horsa glider a few miles to the south near Ranville.

They established a base at Le Bas de Ranville by the evening of 6 June, preparing for assaults on the villages of Longueval and Sainte-Honorine.

In the days and weeks that followed, the RUR would suffer heavy losses during an intense battle in the wood at Cambes-en-Plaine and around the city of Caen.

In July 1944, they were given the Battle Honour Caen, meaning the RUR would lead the 3rd Infantry Division’s advance on the heavily-bombed city, which was one of the first to be liberated.

Almost 200 RUR soldiers died between D-Day and the end of August 1944.

About 70,000 soldiers from Ireland served across a number of areas in the British 2nd Army, Royal Air Force and Royal Navy.

Among them were servicemen in the Guards Armoured Brigade and the Royal Dragoon Guards.

The only Irishman to receive the Military Cross for his actions on 6 June 1944 was Maj Redmond Cunningham, of 79 Assault Squadron, from Waterford.

His efforts to clear German defences and mines at Queen Red Beach helped the RUR’s advance.

Maj John Aldworth, born in County Cork, was killed in action on 7 July leading the RUR’s initial attack on Cambes Wood.

Thousands of Irish diaspora soldiers also fought on D-Day in the US and Canadian militaries.

There are 195 Royal Ulster Rifles soldiers recorded as having graves or their names remembered on memorials in Normandy who died between 6 June and 25 August 1944.

The Commonwealth War Graves Commission cares for such sites from both world wars in northern France, including soldiers who had fought around Dunkirk.

Many graves of Northern Ireland and Irish soldiers from Operation Overlord can be found in cemeteries in Caen, Ranville and Bayeux.

On D-Day, two RUR soldiers were killed, both English-born servicemen.

The regiment’s efforts in the liberation of Caen and the surrounding area is remembered by monuments near Ranville and Cambes-en-Plaine.

There is also a road named in its honour, Chemin des Royal Ulster Rifles.

The main British Normandy Memorial at Ver-sur-mer records the deaths of more than 22,000 service personnel.