[2] Leichhardt was born on 23 October 1813 in the hamlet of Sabrodt near the village of Trebatsch, today part of Tauche, in the Prussian Province of Brandenburg (now within the Federal Republic of Germany).

[3] He was the fourth son and sixth of the eight children of Christian Hieronymus Matthias Leichhardt, farmer and royal inspector and his wife Charlotte Sophie, née Strählow.

[4] In September 1842 Leichhardt went to the Hunter River valley north of Sydney to study the geology, flora and fauna of the region, and to observe farming methods.

After returning to Sydney early in 1844, Leichhardt hoped to take part in a proposed government-sponsored expedition from Moreton Bay to Port Essington 300 kilometres (190 mi) north of Darwin.

Accompanied by volunteers and supported by private funding, he left Sydney in August 1844 to sail to Moreton Bay, where four more joined the party.

[6][7] After a nearly 4,800-kilometre (3,000-mile) overland journey, and having long been given up for dead, Leichhardt on 17 December 1845 arrived in Port Essington, where a company of Imperial marines was stationed.

A memorial to John Gilbert, one of Leichhardt's companions on this journey, can be found on the north wall of St James' Church, Sydney.

Under the title Dulce et Decorum Est Pro Scientia Mori (a variation on the more commonly seen Dulce et decorum est pro patria mori) the inscription on the monument, which was "erected by the colonists of New South Wales" reads: "in memory of John Gilbert, Ornithologist, who was speared by the blacks on 29 June 1845 during the first overland expedition to Port Essington by Dr Ludwig Leichhardt and his intrepid companions".

However, after covering only 800 kilometres (500 mi) the expedition team was forced to return in June 1847 due to heavy rain, malarial fever and famine.

[12] Faced with failure, Leichhardt seems to have suffered a nervous breakdown, and Aboriginal guide Harry Brown effectively took over as leader of the party, taking them successfully back to the Darling Downs.

Soon afterward, on 24 May, the Royal Geographical Society, London, awarded Leichhardt its Patron's Medal as recognition of 'the increased knowledge of the great continent of Australia' gained by his Moreton Bay-Port Essington journey.

I have worked for the sake of science, and for nothing else.In 2012 the National Museum of Australia purchased the medal awarded to Leichhardt by London's Royal Geographical Society in 1847.

[16][17] The party was last seen on 3 April 1848 at Allan Macpherson's Cogoon run, an outlying part of Mount Abundance Station, west of Roma on the Darling Downs.

In 1869 the Government of Western Australia heard rumours of a place where the remains of horses and men killed by indigenous Australians could be seen.

During David Carnegie's expedition through the Gibson and Great Sandy Deserts in 1896 he encountered some Aborigines who had among their possessions an iron tent peg, the lid of a tin matchbox and part of the ironwork of a saddle.

[4] In 1975, a ranger named Zac Mathias exhibited photographs in Darwin of Aboriginal cave paintings that showed white men with an animal.

Dated 2 April 1874, the letter, received by Sydney clergyman William Branwhite Clarke, was written by W. P. Gordon, a station owner from the Darling Downs who had met Leichhardt in the days before his party vanished.

One detailed story referred to the death of a white man who was leading a party of mules and bullocks along the Maranoa River many years earlier.

[2][30] Leichhardt left a record of his observations in Australia from 1842 to 1848 in diaries, letters, notebooks, sketch-books, maps, and in his published works.

In February 2013 the band Manilla Road released a song called "Mysterium", based on Leichhardt's explorations and disappearance.