Turkey on Wednesday marked 100 years since the start of the Gallipoli Campaign by the Allies in World War I, an event seen now as a glorious victory by Ottoman forces and a crucial moment in the formation of the modern Turkish state.

On March 18, 1915, joint British-French naval forces sought to force their way through the Dardanelles Straits separating Europe from Asia in a bid to take Istanbul, then known as Constantinople.

However the attack was repelled by fierce Ottoman resistance, forcing the Allies to stage a land campaign in April that the Ottoman forces would also defeat in a months-long battle.

Although the Ottoman Empire, allied with Berlin, was on the losing side in World War I and subsequently collapsed, the Gallipoli Campaign is regarded by Turks as a seminal moment in their history.

"100 years ago, history changed," declared the headline in the Hurriyet newspaper.

Addressing a ceremony marking the 100 years at the town of Canakkale on the Dardanelles Straits, Prime Minister Ahmet Davutoglu described the battle as a unifying moment in the history of Turkey.

"The heritage of the Ottoman soldiers who sacrificed themselves will always be carried by all Turkey," he said.

In a sometimes fiercely nationalist speech, Davutoglu portrayed Turkey as a force for good in the world, such as its hosting of over 1.7 million Syrian refugees.

"As long as we breathe, the cruel in the world will not be able to sleep peacefully," he said.

In a later speech at the giant 40-metre (130-foot) high Martyrs' Memorial, he paid tribute to the quarter million Ottoman troops who took part in the campaign.

"The battle showed that there is nothing stronger than a nation ready to die for their homeland and it is impossible to capture such a nation."

- 'Unity, brotherhood and solidarity' -

Turkish warships staged sail-by salutes in the Dardanelles while fighter jets performed aerobatic displays.

The resistance of the Ottoman forces is seen as playing a key role in giving birth to a national conciousness and leading to victory in the War of Independence and the creation of the modern Turkish state in 1923.

Among the commanders at the Battle of Gallipoli was Mustafa Kemal -- later known as Ataturk -- who would lead the creation of the modern state and remains its national icon.

The ceremonies in Canakkale are being backed up by a huge number of television documentaries, press articles and films in a clear government-backed drive to emphasise the Gallipoli Campaign as a heroic victory.

Davutoglu was to watch the premiere of a new Turkish blockbuster film "Son Mektup" ("The Last Letter) about a romance between a Turkish pilot and nurse in the campaign as it goes on nationwide release.

President Recep Tayyip Erdogan described the battle -- which would last nine months with tens of thousands dead on both sides -- as a turning point.

"The unity, brotherhood and solidarity displayed in Canakkale -- in addition to bringing victory -- helped bolster the fighting spirit required especially for our independence war," he said.

The March 18 commemorations kicked off a large programme of events leading up to ceremonies in April, marking when Ottoman forces repelled landings by combined Australian, British, French, New Zealand and Indian troops.

Turkey will host the main ceremony -- expected to be attended by several world leaders -- on April 24 which is a day ahead of the anniversary of the actual landings on April 25, marked in Australia and New Zealand as Anzac Day.

Critics have accused Turkey of cynically shifting the date to overshadow ceremonies expected in Armenia and across the world to remember the 100th anniversary of the mass killings of Armenians by Ottoman forces in World War I.

Turkey has always rejected pressure to accept that the killings were a genocide and shows no sign of changing its position in the anniversary year.