IT has been described as the most tragic event in Australia's history - the Battle of Fromelles in France on July 16, 1916.

More than 5500 Australians were killed, wounded or taken prisoner in a single battle just short of 100 years ago.

The battle was a bloody initiation for soldiers of the newly arrived 5th Australian Division to warfare on the Western Front.

Together with the British 61st Division, the Australians were ordered to attack strongly fortified German frontline positions near the Auber's Ridge in French Flanders.

The infamous ridge, although only 40m high, was the highest feature on the landscape, giving the Germans a commanding view of the Australian and British preparations.

The attack was intended as a feint to hold German reserves from moving south to the Somme where a large Allied offensive had begun on 1 July.

The feint was a disastrous failure.

Australian and British soldiers assaulted along the 4km front from between 80m and 400m of open ground in broad daylight and under direct observation and heavy machine gun and artillery fire from the German lines.

The German defences included concrete blockhouses and a strong redoubt, known as the Sugarloaf, overlooking most of the allied line of advance.

Preparations for the attack were rushed, the troops involved lacked experience in trench warfare and the power of the German defence was significantly underestimated, the attackers beingoutnumbered 2:1.

Almost 2000 Austrtalians were killed in action or died of wounds and some 470 were captured.

This is believed to be the greatest loss by a single division in 24 hours during the entire First World War.

Even before they went over the top, the ill-prepared Australians packed shoulder to shoulder into front-line trenches suffered casualties from German artillery fire and from "drop shorts" fired by their own inexperienced artillery.

Two British battalions lost 140 men to artillery fire before they left their trenches.

Sergeant "Jimmy" Downing of the 57th Battalion recalled: "Hundreds were mown down in the flicker of an eyelid, like great rows of teeth knocked from a comb… men were cut in two by streams of bullets… It was all over in five minutes."

The 15th (Victorian) Brigade was destroyed within 15 minutes, entire companies of infantry being virtually annihilated.

Their commander, Brigadier General Harold "Pompey" Elliott, who had earlier expressed misgivings about the attack, was speechless with grief the following day, "the tears streaming down his face, as he shook hands with the returning survivors".

Official war correspondent Charles Bean recorded after meeting Elliott: "I felt almost as if I were in the presence of a man who had just lost his wife."

One of Elliott's battalions, the 60th, had gone into the attack with 887 officers and men.

When the survivors gathered at brigade headquarters the following afternoon, only one officer and 106 men answered the roll call.

A renewal of the attack by the 61st Division early on July 20 was cancelled, after it was realised that German counter-attacks had already forced a retirement by the Australian troops to the original front line.