Anzac Day commemorates the involvement of Australian and New Zealand troops in a World War I campaign on the Gallipoli peninsula in Turkey.

The campaign's aim was to land troops on the Aegean sea side of the peninsula then move inland to take the Turkish forts which secured the Dardanelles - a narrow strait which became tactically vital on Turkey's entry into the war - on the other side of the peninsula.

The landings near Ari Burnu in Turkey took place at dawn on April 25, 1915. While they began well, steep rugged terrain and a fierce counter-attack by Turkish forces prevented the Allied troops from making much progress.

They dug in, and over the course of the next seven and a half months more than 8,000 Australians and 2,500 New Zealanders died in the fighting. British losses were far greater - around 21,000 men - and in all the Allies lost more than 46,000 men during the campaign at Gallipoli.

Around 86,000 Turks died in defence of the peninsula.

The Allies eventually withdrew from Gallipoli in December 1915 having failed to achieve their objective.

The landing site is now known as Anzac Cove.

Involvement by Australians in the campaign is commemorated at dawn services around Australia on April 25. It is a national holiday and marks the involvement of Australian troops in all theatres of war.

Symbol of nationhood

Coming just 14 years after federation, the Gallipoli campaign was one of the first international events that saw Australians taking part as Australians. As such, it has been seen as a key event in forging a sense of national identity.

Reports from the frontline certainly gave the impression that the Australian troops were fighting above their weight.

Phillip Schuler, war correspondent for The Age newspaper, wrote of the Australians' "unflinching courage" and "magnificent gallantry".

Reporting on the battle of Gaba Tepe, he wrote: "They held and won the position. Can more be said; can greater acknowledgment be made?

"The young army's first battle found it cruelly christened; it left the men uncrushed, victorious, and ready to face the foe. It may be called the battle of Gaba Tepe, and in those words, or one of them at least, is sufficient to commemorate the deed. Gaba meaning great."

While the link between Anzac Day and nationhood is rejected by some, it has been reinforced in recent years by the views of the Returned and Services League (RSL), historians and politicians.

WWI battlegrounds in Europe, in particular the shores of Gallipoli, draw young Australian tourists in their thousands around April 25. The journey is seen by many as a rite of passage.

In Australia, while fewer and fewer veterans are able to march in Anzac Day parades, the dawn services around the nation and the parades that follow them have been embraced by their descendents and are enjoying a renaissance over the past decade.