Including prisoners and wounded, the New Zealanders suffered nearly 1,400 casualties in the battle, one of the most brutal of the European theatre.
Looming over the cemetery was the squat, fortress-like monastery of Monte Cassino, which became an object of fear and hatred for many Allied troops during the five months that they tried to take it from the Germans in 1944.
Looking up at the stone abbey, which was built in the sixth century but was bombed into oblivion in the war and rebuilt afterwards, Charlie Kenny, 92, who served with the 23rd Battalion, said: "I would blow the bugger up. It was the toughest part of the war for us.
We were living in filth."
The former infantryman, from Timaru, was visiting Monte Cassino for the first time since he fought there 70 year ago.
"Our tank crews got "cooked up" and I still can't stand the smell of roast pork. There was a smell of death that I will never forget," he said.
The New Zealanders were involved in house-to-house fighting amid the rubble of Cassino town, with the Germans terrifyingly close and liable to pop up unexpectedly from cellars and basements concealed by smashed buildings.
"They were about 75 yards away. It was bloody terrible fighting in the rubble. The Germans built their tanks into the sides of the houses. Anyone who says he wasn't frightened is a bloody liar," said Mr Kenny.
The ceremony at the Commonwealth War Cemetery, attended by around 40 veterans as well as hundreds of their relatives and members of the New Zealand military, marked the 70th anniversary of the monastery finally being captured.
The honour of being the first troops to enter the shattered stone building was given to the Poles, whose country had suffered grievously under Nazi occupation.
Standing on a terrace in the monastery, Prince Harry surveyed the steep, rocky slopes on which thousands of British, New Zealand and other Commonwealth troops fought and died in the desperate campaign to wrest control of the stronghold from the Germans.
Squinting against the sun, the prince was shown where the Allies tried to advance from the valley below, all the time under the withering fire of Spandau machine guns, mortars and artillery.
"It really dominates the valley," the prince said, as he looked down over Cassino town, which was smashed to rubble in the fighting, as well as the town's railway station, where a battle raged for days and cost the New Zealand 28 Maori Bn particularly dearly.
The monastery, perched on top of a 1,700ft high mountain, was tenaciously defended by battle-hardened German forces between January and May of 1944.
Its almost impregnable position and great height allowed them to pour devastating fire down on the Allies, holding up the advance on Rome.
At an exhibition inside the monastery, which showed how it was reduced to rubble in Feb 1944 after the US Air Force was ordered to bomb it in order to deny the Germans a strategic look-out, he said: "Unbelievable. They knocked the whole thing down. They flattened it."
The prince, wearing a Household Cavalry dress uniform, performed his first Maori hongi greeting, pressing noses with Sir Jerry Mateparae, New Zealand's Governor General.
Maori soldiers, sailors and airmen performed a traditional karanga ceremony, requesting permission to enter the sacred land of the cemetery, as they advanced towards the Cross of Sacrifice at one end.
With wild-eyed looks reminiscent of the haka, they performed a Maori chant known as the maimai aroha, which expresses sorrow and respect for those who have died.
A pair of Maori servicemen twirled traditional wind instruments above their heads, making a whirring noise, as the sun shone on distant ridges still capped with snow.
Introduced as "His Royal Highness, Prince Henry of New Zealand", the fourth in line to the throne then laid a wreath of red poppies against the Cenotaph, as a Maori choir sang and the New Zealand flag was lowered to half-mast in front of about 40 veterans.
He stood stiffly to attention as a minute's silence was observed and the Last Post played.
The ceremony was led by Rev Lance Lukin, the principal chaplain for the NZ Defence Force.
"We come from the utmost ends of the earth to honour those who made the ultimate sacrifice in this place," he said. "As we are gathered in this beautiful setting, we try to imagine the scene that confronted our young Kiwi boys 70 years ago."
"Cassino was a defenders' dream and an attacking army's nightmare," said Trevor Matheson, New Zealand's ambassador to Italy.
The Kiwis confronted "mud, rain and snow, and a deeply entrenched and determined enemy," he said.
Wally Malcolm, 92, was captured by the Germans on the Adriatic coast of Italy and spent two years in a POW camp.
He came to Monte Cassino to pay his respects to friends buried there.
"Some of my mates didn't make it. I managed to return home, got married and had a family - three boys and a girl. But all that was denied to them," said Mr Malcolm, from Hawkes Bay, who after the war became a dairy farmer.
In his address, Sir Jerry Mateparae described Cassino as "a hard fought and desperate battle" in which the 28th Maori Battalion suffered particularly heavy casualties.
During the fighting for Cassino railway station, "only 66 men returned to the Allied lines out of 200 who started the assault."
Robert Gillies, 89, who fought with the Maori Battalion, was pacing along the rows of grave stones looking for the one marking a friend called Jonny.
He recalled trying to cross the Rapido river near Cassino under heavy fire.
"The Germans had box mines laid all along the bank and we set them off. "Some men lost their feet, others were killed. There was a turret ahead with a Spandau machine gun and they just raked the whole bank."
Several British veterans of the battle were also at the ceremony.
John Dudley, 89, from Chatham in Kent, was serving as a lance corporal with the East Surrey Regt when he and his unit crossed the Rapido river, near Cassino town, at midnight on May 11, 1944 in canvas-hulled boats.
"We suffered 78 casualties out of a battalion of 200 men. 'A' Company was almost completely wiped out. I was one of the few survivors. The boats were hit by machine gun fire and torn by underwater barbed wire. We were loaded down with packs and ammo so a lot of men drowned."
Wounded three times during the Italy campaign, he said: "It was horrible. We were terrified. We were being hit by Spandau machine guns which could fire 1,000 rounds a minute. They only stopped when the barrels seized up."
