Prince Harry has reacted with amazement at the damage wreaked on an historic monastery during one of the Second World War's most important battles.

Harry is marking the 70th anniversary of the Battle of Monte Cassino by visiting the site of the Italian conflict and joining Poles, Britons and New Zealanders in honouring their war dead.

The battle was a crucial campaign that saw Allied forces launch four battles in 1944 to destroy Nazi forces holding a strategically important rocky outcrop, home to the 1,400 year-old Benedictine monastery of Monte Cassino. Heavily defended, it was an obstacle to the Allies' progress to Rome as they fought their way north through the country.

The fighting force consisted of many nations from Americans and British, to Indians, Poles, Canadians, and French from North Africa, Indians, Gurkhas and New Zealanders but all had to contend with icy mountain terrain, mines and bombardment from Nazi forces. Progress was slow and the conflict claimed many lives becoming the bloodiest battle in Europe with an estimated 250,000 men killed or wounded.

Controversially the monastery was heavily bombed and destroyed in a bid to make a breakthrough, but the move failed and the holy site was later rebuilt.

Harry visited the famous Monte Cassino and was given a guided tour by Father Antonio Potenza, the Abbott's secretary.

As he walked into an exhibition chronicling the destruction of the holy site he saw a huge black and white image of its ruins and said :"Unbelievable - they knocked the whole thing down."

The 6th century monastery was rebuilt after the war and was restored to the original plans.

Today, Monte Cassino is a working place of worship and continues to house the suriving relics of Saint Benedict.

During the tour Harry paused to view a manicured rose garden - before crowds burst into a spontaneous rendition of the British national anthem.

And later he was taken to a balcony to view the spectacular surrounding countryside.

Harry also attended a reception in the monastery for injured Italian servicemen and women who will be taking part in his Invictus Games, a paralympic-style competition for wounded military which will be staged in September.

Airforce Colonel Marco Iannuzzi, 36, who is co-ordinating Italy's team for the event said: "Next year I'm getting married and he said something funny."

The Colonel who was joined by his fiancee Anna Lucia, 27, added: "He asked me how I proposed and I said it was last Valentine's Day in Paris and he said 'that was very romantic'.

"He asked me: 'Why don't you get married in London?' and I said: 'Why not'."

The Colonel walks with the aid of a stick after breaking his back in a plane crash in 2000 but is hoping to compete himself in a swimming event.

At the end of their chat Harry said: "I'm looking forward to seeing you in London - bringing the sunshine."

Colonel Monica Contratta in the Fusiliers told Harry how she lost her leg in Gulistan, Afghanistan in 2012 under mortar fire when insurgents attacked the base.

She was saved by a colleague who dragged her to a bunker but was hit in the intestine, hand and femur artery.

The servicewoman has a prosthetic leg and her hand was rebuilt using a bone from her thigh.

She learnt to walk again after seven months and now runs 100 metres with a blade prosthetic.

She told Harry: "I am a bionic woman.

When he asked: "How fast do you run the hundred metres," she replied: "I cant tell you."

He said: 'It's a secret? Then we've got real competition."

Later she said: "He's very handsome. Can I swap my boyfriend for him?"