The families of soldiers who served in the Gallipoli campaign of World War I, along with world leaders, are streaming onto the battle sites for ceremonies marking 100 years since the British-led invasion.

Representatives of countries that once faced off in one of the most iconic events of the war will honor the dead in a joint ceremony Friday, on the eve of the centenary since troops landed on beaches here.

Turkish President Recep Tayyip Erdogan will make a speech along with Australian Prime Minister Tony Abbott, with Britain's Prince Charles and Prince Harry in attendance.

The doomed Allied offensive aimed to secure a naval route to Istanbul through the Dardanelles, and take the Ottomans out of the war. It resulted in over 130,000 deaths.