Details of the find by a team from Queen’s University Belfast, revealed exclusively to the Irish Examiner, show the underground bunkers, built around 1915, could have accommodated sleeping quarters for up to 300 troops.

Academics specialising in archaeology and geology started out on their mission after acquiring historical maps which showed huge fortifications were built at Lynch Camp, Kilworth, shortly after the outbreak of the war.

After acquiring permission from the Department of Defence and the Defence Forces to visit the camp, located halfway between Fermoy and Mitchelstown, they carried out their first reconnaissance of the land in October 2013 and followed it up with a week-long detailed examination last July.

“We were just blown away with what we found. It is certainly the best preserved in Ireland and is so significant that it could be bigger than anything found in Salisbury Plain (a huge British Army training centre in Wiltshire, close to Stonehenge). It’s a really significant find,” said Dr Alistair Ruffell, a geology expert who was co-supervisor on the project.

He and his colleagues used ‘Time Team-type’ technology to work out what the underground fortifications consisted of.

Among the technology employed was aerial mapping, GPS, and geophysics, which is ground-penetrating radar.

It enabled the team to see the extent of the massive underground bunker and the trenches, which today are almost totally obscured by heather and gorse.

He estimates the fortifications ran for a couple of kilometres and that British Army engineers also constructed ‘enemy trenches’ on an elevated slope opposing them, which troops were then ordered to capture.

Dr Ruffell believes lookout towers, still present at the camp, were used by officers to direct their troops coming out of the bunkers onto enemy positions. The Germans were more technically adept at building bunkers and trenches early in the war.

Dr Ruffell said the Kilworth fortifications were built to show troops the reality of life in the trenches, as well as enabling them to carry out pre-battle training in conditions as realistic as they would meet at the front.

He said the ‘friendly trench’ was zig-zag and consisted of three forward machine-gun posts. If these posts were overrun, troops could retreat to the main trench which was linked to the underground chamber.

Troops training at the site “would sleep in the bunker on wooden beds and would cook food on little paraffin burners”.

He said the terrain in Kilworth was also ideal, because it was similar to many battlefield areas troops would later encounter on the Western Front.

The archaeologists have not conducted any excavations due to a risk of any unexploded shells buried there from that era, or from later on as Kilworth had been a military training camp from the late 1890s to the present day.

He credited the discovery to PhD student Heather Montgomery, who is enthralled by battlefield archaeology and persuaded her colleagues that an investigation of the Kilworth site might be worthwhile.

“It was quite emotional to be in the trenches, for obvious reasons. These were sometimes the last places the young men from Ireland practised in before they went, often to not return,” Dr Ruffell said.

A large British garrison barracks was built in the nearby town of Fermoy in 1806 and some of the soldiers trained there fought in the Battle of Waterloo, nine years later. Towards the end of that century, the British military identified Kilworth as an ideal training camp and purchased 14,000 acres of land there.

Firing ranges opened there in 1886, traces of which Dr Ruffell said still exist.

It became a significant training camp a few years later and a large number of soldiers who undertook manoeuvres had fought in the Second Boer War (1899-1902).

Some local families still possess remarkable pictures of huge columns of soldiers, numbering several thousand, marching along the former main Cork-Dublin road, close to the Moorepark agricultural research station, on their way to Fermoy following First World War training exercises in Kilworth.

The Department of Defence and the Defence Forces said they were happy to facilitate the archaeologists in their work. It is unclear, at present, what further research, if any, the archaeologists will undertake.

In recent years, the camp again become a significant training centre for the Defence Forces and a €1m state-of-the-art automated firing range, installed by Swedish company Saab, opened last year.

The camp has also been refurbished to accommodate 320 troops for exercises, at any one time, and possesses state-of-the-art catering and fitness facilities.

Around 4,500 members of the Defence Forces are assigned to Kilworth for training every year, including the Naval Service and the Ranger Wing.