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Life behind garda ring of steel...

IT WAS the biggest gathering of cops in history -- so much so that the O2 was turned into the world's largest barracks.

These extraordinary pictures show the sheer scale of the massive security operation that went into to ensuring Queen Elizabeth's visit to Ireland went off without a hitch.

It was all part of the joint security op which also brought US President Barack Obama to Ireland, during one of the greatest periods in our history.

And in case you wondered what it takes to feed 8,000 Gardai, have a look at the canteen -- the tables on the ground beneath the seated area at the O2.

The pictures, published in the Garda Review this week and taken by the Garda Photographic Section, show thousands of officers attending briefings at the O2.

And two images (far right) by Garda Brian Breathnach show how officers searched drains and underground for anything suspicious before the queen's arrival.

They also vetted thousands of residents living alongside the route the queen was due to take. For the visit itself, thousands of gardai became a ring of steel for the massive security operation.

"This was to be the biggest event in the State. The resources required were made available. The members worked effectively to prevent any embarrassing scenes," Supt Joe Gannon, of Pearse Street Garda Station, told the Garda Review.

"A plain-clothes unit apprehended men carrying a large bag of eggs they intended to throw, and when the queen was coming over O'Connell Bridge someone tried to throw fruit but a uniformed member apprehended him."

Asst Commissioner Michael Feehan (Dublin Metropolitan Region) was in charge of the operation while the queen was in Dublin.

"Many people put their shoulder to the wheel in what was probably the biggest event in their career. They did deliver."