The first centenary commemoration has been held at Gallipoli, where the Prince of Wales and Prince Harry delivered stirring readings against the stunning backdrop Dardanelles Strait where the Allies landed in 1915.
The commemoration at the Cape Helles memorial at the southern tip of the Gallipoli Peninsula was hosted by the UK Government and Northern Ireland in partnership with the Commonwealth War Graves Commission.
The site is close to the the strategically vital entrance to the Dardanelles Strait, which the Allies had planned to open up during the invasion to gain access to the Sea of Marmara Shortly before the service began the Royal Navy Guard made a sail past, through the strait to the Aegean Sea.
The guard was drawn from the Ship's Company of HMS Bulwark, lying off Cape Helles with New Zealand's HMNZS Te Kaha, seven Turkish and three Australian ships. Seven Turkish Air Force jets then flew in formation overhead.
Naval launches patrolled the shores as VIPs and dignitaries arrived and coaches carrying attendees and media were stopped by authorities every few kilometres and had their accreditation scrutinised.
On arrival, journalists were searched and patted down before they were allowed in.
The Prince of Wales and Prince Harry, dressed in full uniform, arrived just before 5.40pm local time.
Prince Charles has been to Gallipoli before, but it was Prince Harry's first commemoration. The pair stopped to read some of the 21,000 names on the memorial before taking their seats.
Turkish President Tayyip Erdogan then arrived, surrounded by a snaking convoy of heavily fortified coaches with rooftop snipers.
Around the picturesque monument, snipers, soldiers and armed jendarm stood in the lush green fields beneath blooming spring trees.
He was followed by representatives of the armed forces from the various Commonwealth countries who fought and died at Gallipoli.
Prime Minister John Key and Australian Prime Minister Tony Abbott were seated in the front row, though not together.
The service, which started an hour late, was led by The Reverend Dr David Coulter QHC, Chaplain General to Her Majesty's Land Forces.
But the first speaker was Prince Charles, who read extracts from John Masefield's Gallipoli from 1916.
Air Chief Joe Marshall, vice chairman of the Commonwealth War Graves Commission then spoke, saying it was the organisation's duty to honour all those who died at Gallipoli - no matter where they were from or if they died on land or at sea.
"Today, we recognise their courage and remember their sacrifice," he said.
The ode To The Fallen was read and The Last Post played by a trumpeter from Prince of Wales's Division Band before the HMS Bulwark fired a shell from offshore to signal a minute's silence - it's explosion rippling across the undulating Gallipoli Peninsula.
The wreath-laying cemetery started with Turkish soldiers in distinctive domed helmets laying a wreath made of poppies in the shape of their nation's flag.
Prince Charles followed, laying circle of poppies with a handwritten note saying "In everlasting memory, Charles" - at the base of the cenotaph. Leaders of Turkey, Ireland and Pakistan stepped forward to lay their wreaths before Mr Key and Mr Abbott laid a joint tribute.
Prince Harry also spoke, reading the poem, The Bathe written by A P Herbert in 1916.
The Helles Memorial was built in 1924 and serves two functions.
Firstly, it is the Commonwealth battle memorial for the whole Gallipoli campaign and secondly, it is a place of commemoration for British and Commonwealth servicemen who died there and have no known grave. There are also memorial panels for those buried at sea.
There are more than 21,000 names on the memorial, designed by John Burnet.
Among the names are five Victoria Cross recipients, five soldiers who played rugby at an international level before they were killed and a first-class cricketer.
Cape Helles was an integral part of the Gallipoli campaign. On 25 April 1915, as the Anzacs stormed the beach near Ari Burnu, British forces were launching an amphibious attack at Cape Helles.
THE PRINCE OF WALES' READING: Extracts from Gallipoli, by John Masefield, 1916
Ship after ship, crammed with soldiers, moved slowly out of the harbour, in the lovely day, and felt again the heave of the sea. All the thousands of men aboard them, gathered on the deck to see, till each rail was thronged.
These men had come from all parts of the British world, from Africa, Australia, Canada, India, the Mother Country, New Zealand and remote islands in the sea. They had said good-bye to home that they might offer their lives in the cause we stand for.
In a few hours at most, as they well knew, perhaps a tenth of them would have looked their last on the sun, and be a part of foreign earth or dumb things that the tides push. Many of them would have disappeared forever from the knowledge of man, blotted from the book of life none would know how, by a fall or chance shot in the darkness, in the blast of a shell, or alone, like a hurt beast, in some scrub or gully, far from comrades and the English speech and the English singing.
And those not taken thus would be under the ground sweating in the trench, carrying sand-bags up the sap, dodging death and danger, without rest or food or drink, in the blazing sun or the frost of the Gallipoli night, till death seemed relaxation and a wound a luxury.
As each ship crammed with soldiers drew near the battleships the men swung their caps and cheered again, and the sailors answered, and the noise of cheering swelled. They left the harbour very, very slowly; this tumult of cheering lasted a long time; no one who heard it will ever forget it, or think of it unshaken. It broke the hearts of all there with pity and pride.
PRINCE HARRY'S READING - The Bathe by A. P. Herbert, 1916:
The poet, novelist, playwright and activist Alan Patrick Herbert joined the Royal Naval Volunteer Reserve when war broke out and landed at Gallipoli as an officer in the Hawke Battalion of the Royal Naval Division in May 1915. Recovering in Britain from an injury, Herbert wrote about his experiences at Gallipoli, publishing Half-Hours at Helles in 1916, which included this poem.
Come friend and swim. We may be better then, But here the dust blows ever in the eyes And wrangling round are the weary fevered men, Forever made with flies. I cannot sleep, nor even long lie still, And you have read your April paper twice; Tomorrow we must stagger up the hill To man a trench and live among the lice. But yonder, where the Indians have their goats, There is a rock stands sheer above the blue, Where one may sit and count the bustling boards And breathe the cool air through; May find is still good to be alive, May look across and see the Trojan shore Twinkling and warm, May strip, and stretch, and dive. And for a space forget about the war. Then will we sit and talk of happy things, Home and 'the high' and some far fighting friend, And gather strength for what the morrow brings, For that may be the end. It may be we shall never swim again, Never be clean and comely to the sight, May not untombed and stink with all the slain. Come, then, and swim. Come and be clean to-night.