Relatives of soldiers who fought and died in that conflict spoke of their pride and sadness at a special commemoration service attended by 2,000 people in the city's cathedral.
Prince William said he wanted to 'honour the fallen of all nations' and praised the international cooperation, saying the battle symbolised Britain's 'Entente Cordiale' with France.
He said the troops brought 'hope and optimism after four long years of bloodshed and stalemate'.
But French President Emmanuel Macron, who is from Amiens, did not interrupt his holiday to attend.
Mrs May paid tribute to the 'courage, bravery and skill' of the soldiers. This is how the decisive battle, which marked the beginning of the end of the war, unfolded . . .
Of all the great and bloody engagements of World War I — from Mons, the Marne, and Ypres, to the Somme and Passchendaele — Amiens is the forgotten battle
Of all the great and bloody engagements of World War I — from Mons, the Marne, and Ypres, to the Somme and Passchendaele — Amiens is the forgotten battle, lasting for just four days.
And yet it was one of the most crucial. The Battle of Amiens was the key that unlocked the Western Front and marked the beginning of the end of the so-called 'war to end all wars'.
It kicked off the Hundred Days Offensive — a three-month Allied onslaught that overwhelmed the enemy and paved the way to victory and the signing of the Armistice on November 11, 1918.
It also marked the end of trench warfare and saw the birth of high-tech conflict.
By August 1918, after four years of intense shelling, millions of dead and wounded, and untold misery and agony on both sides, the Front, in Northern France between the Allies and the Germans, had barely moved.
Suddenly, at Amiens — a tactically vital city and railway junction on the River Somme, 40 miles from the Channel — the scales tipped in the Allies' favour.
Prince William and Theresa May (pictured today) led tributes to World War I troops yesterday as they marked the centenary of the Battle of Amiens
With a coherent strategy, and advances in tactics, backed by more than 500 tanks, 2,000 heavy guns and a fledgling but highly effective air force, the combined might of 75,000 British, Australian, Canadian, American and French troops were able, at last, to make inroads into enemy territory on a 14-mile front.
The presence of the Americans, who had declared war on Germany in April 1917, did a huge amount to boost manpower, firepower and, most importantly, morale.
The battle began on August 8, 1918 — later described as 'the blackest day of the German Army' by General Erich Ludendorff.
Just the day before fighting started, Kaiser Wilhelm, the German emperor, had warned Ludendorff: 'We have reached the limits of our capacity. The war must be ended.'
Ludendorff's spring offensive against the Allies, in March and April of that same year, had very nearly swung the war in the Germans' favour, after an injection of hundreds of thousands of troops.
But it soon ran out of steam and, by late summer, the Germans were exhausted.
Pictured: Soldiers wear gas masks as they carry a wounded colleague through the fields of Amiens
The Allied counter-offensive beginning at Amiens was, by contrast, a triumph. On that first day, the Allies advanced over seven miles — a vast distance given the terrible bloodshed wasted on advances of mere hundreds of feet in the previous four years — capturing more than 400 guns and taking 12,000 German prisoners.
Captain Edwin Francis Trundle of the Australian Imperial Force, one of three brothers who survived the war, wrote to his wife Louisa: 'During the last few days, we have advanced over 12 miles . . . up to the present, everything has gone excellently and everyone is in high spirits . . . I followed the attacking infantry with a team of 36 pack mules carrying ammunition forward. Ever since then, we have kept continually moving forward.'
The presence of tanks was key to that success. Invented by the British and first used at the Battle of Flers-Courcelette in September 1916, by the time of Amiens the Allies had 580 tanks in action — more than in any single battle to that date.
And the generals showed that they had learned from the costly strategic blunders of the previous years. Instead of trying to soften up the enemy before an offensive with a heavy artillery barrage — a tactic which invariably gave away their position and often their plans — they deployed the tanks in a surprise attack, supported by howitzers, field guns and heavy guns which zeroed in on the Germans' lesser firepower of just 530 guns.
Amiens was destroyed after the battle and stood in ruins after the end of the Great War
The accuracy of the Allied fire was helped massively by aerial reconnaissance photographs.
At the beginning of the war, the RAF hadn't even existed — it was founded on April 1, 1918 — but by the time of Amiens, only four months later, it was already on its way to becoming a lethally efficient outfit.
'In just four years, aeroplanes were turned from unreliable birdcages with no clear purpose into hardwearing machines capable of multiple tasks,' according to Joshua Levine, author of Fighter Heroes Of WWI.
The combined Allied force of infantry and tanks was backed by 1,900 Allied planes making elegantly coordinated raids over enemy lines.
An elaborate Allied decoy had also been set up. Two battalions were sent to Ypres in Belgium, some 75 miles north-east of Amiens which fooled the Germans into thinking that it was from here that an offensive would be launched.
The Allies further concealed their actions at Amiens by moving soldiers only at night. Even to their own men, Allied officers referred to the Battle of Amiens as a 'raid', not an offensive — to stop loose tongues spreading the truth of the massive new attack. Notices to the men were stamped with the blunt words: 'Keep Your Mouth Shut.'
In the event, the Germans were so surprised by the initial attack, launched in thick fog at 4.20am while some of them were eating breakfast, that it took them five minutes — an eternity in battle terms — before they returned fire.
By then, the Allies were moving so quickly that they had left the area the Germans were firing at.
Victory in the Battle of Amiens was quick and decisive — and dealt a massive blow to German spirits.
General Ludendorff later recalled how, to his horror, he saw his soldiers who were running away from the front line yelling at their officers: 'You're prolonging the war!'
Fellow Germans who were ordered in to replace them were, he wrote, derided as 'Blacklegs' by the deserting troops.
Alexandra Churchill, author of In The Eye Of The Storm: George V And The Great War, to be published next month, describes the Battle of Amiens as hugely important because: 'For the first time, the British Army combined everything they had learnt during the previous four years and employed it on a large scale . . . to deliver a stunning blow to the beleaguered enemy.
'What was just as important though, was that, rather than continue to press and advance for diminishing returns, as on the Somme and at Passchendaele, the damage was done and the attack called off.
'This saved valuable resources in men and material and meant that the British Army could regroup and then strike again.
'This they would continue to do for the rest of the year, bringing victory closer than most had previously dared to believe.'
Yet for all its success, Amiens led to terrible casualties: 22,000 British Empire soldiers and 22,000 French troops were killed or injured. There were 75,000 German casualties and 13,000 taken prisoner.
One soldier, Lance Corporal Frederick Palmer, 32, from Chingford, Essex, was wounded by a shell on the first morning of the battle. He died two days later.
Before the battle, Palmer, serving with the 54th Canadian Infantry Battalion, wrote a postcard home to mark the first birthday of his daughter Freda — a child he'd never seen as she'd been born two months after he left for the Front.
'My very sweet darling,' he wrote, 'just a line to wish you all happiness and many, many happy returns on your birthday.
'I shall be with you on your next one and then we shall have a lovely party for my little daughter. Be a good girl till I come back. From your loving Daddy with lots of kisses xxx.'
Frederick Palmer's granddaughter, Pat Bates, 61, attended the service at Amiens Cathedral yesterday for what she described as 'a funeral for him that I can attend'.