Today marks the 100th anniversary of New Zealand's darkest day on a battlefield: The Battle of Passchendaele, which was also known as the Third Battle of Ypres.
Officially 843 New Zealanders died and over 1700 were wounded in just the first few hours of October 12th 1917, as allied troops tried and failed to take the village of Passchendaele in Belgium.
The battle eventually claimed the lives of nearly 2000 New Zealand soldiers.
Percy Withers from Geraldine was at Passchendaele serving with the Otago Regiment, 1st New Zealand Expeditionary Force. He was my grandfather and he went to war at the age of 20.
He wrote of his experiences years later.
"Here the devastation was, if possible, more complete - it was the devastation of today and the day before, with the reek of high explosives pervading everything and the sickly smell of dead men and dead horses and a murky red sunset, a forboding of things to come in the weeks ahead."
A New Zealand military historian, Ian McGibbon said while the plan to take Passchendaele was not an impossible task, a number of things conspired against success.
This included very wet weather that turned the countryside into a quagmire, the failure to cut barbed wire protecting the German line and artillery not being able to be used accurately to bombard the enemy's dug-in positions before the attack.
"This explains while the British divisions failed on the 9th of October and it is also the reason why the attack of the 12th of October made by the New Zealanders failed as well."
Veteran Joe Cody was with the 1st Canterbury Battalion.
"The Passchendaele that the diggers knew was a sea of mud, dead mules, the dead horses, the dead men lying in long rows with machine guns that got them, shell holes and while the moon would be a summer resort compared to the desolate place I knew."
Another veteran of Passchendaele, John Moloney described it as the world's worst battlefield, which became the grave of everyone's hopes.
"It was a terrible disaster. The military science of the British Army was at its lowest ebb and in fact if anyone had had any sense and seen over the battlefield they would never have let the attack go on the 12th, it was a most terrible attack."
Mr Moloney said no allied soldier stood a chance.
"The machine guns cut them to pieces leaving their bodies swathed like butterflies against the wire."
John A Lee was there with the New Zealand Division, and said the verdict of history was that the higher command did not know just how impassable the conditions were.
Percy Withers wrote the horror, the mud and the desolate wastes of the Ypres Salient will indeed persist as part of one's life, a part that one does not and can not altogether forget.
"The mind has cast off the details but memories remain of mile after mile of blood soaked, stinking mud."
Historian, Ian McGibbon said that while 843 New Zealanders were officially listed as killed in the first few hours of the offensive, his research into the wounded shows that another 114 men died over the next three months from wounds received on that morning.
"They went to ground in shell hole all across the battlefield, wounded men lying in shell holes. It was a terrible situation and some of them would have been sniped, the Germans were up on the higher ground, so if they lifted their head they would have been hit by a bullet probably because some of the soldiers said the Germans' shooting was remarkably accurate."
The next two days were spent recovering the dead and wounded after an unofficial truce.
"In the bog it took six men to carry one stretcher, it was just horrendous."
New Zealand troops returned to the line they started out at and remained there in extreme conditions for another ten days.
Dr McGibbon said morale was at its lowest point on the Western Front.
"There was sort of recriminations as to who was responsible."
He also said General Godley became the focus of the blame amongst the troops.
Canadian troops eventually captured what was left of Passchendaele in early November, but six months later the Germans retook it and held it until just before the end of the war.
Percy Withers who was promoted from Lance Sergeant to Sergeant in the field, wrote after the war of the appalling cost to both sides.
"And we may wonder, with what result, to what end? One answer was given by a German General, Ludendorff, who wrote in his memoirs that Passchendaele at last broke the morale of the German army."
The New Zealand National Commemorative service will be held in Belgium tonight at the Tyne Cot Cemetery and will be followed later by a Sunset ceremony at the New Zealand Battlefield Memorial at Buttes New British Cemetery at Polygon Wood.
In this country, a ceremony will take place at the Pukeahu National War Memorial Park at 3pm, followed by the unveiling of a Belgian Memorial.
Other services will be held around the country, including one at the Auckland War Memorial Museum at 11 am.
Interviews with soldiers from the archives is provided from Ngā Taonga Sound & Vision