The party started from Hume's residence at Lake George in October 1824, crossed the rivers Murrumbidgee, Hume (Murray), Mitta-Mitta, Ovens, and Goulburn and reached the western arm of Port Phillip near the site of Geelong. They made a mistake as to their whereabouts, and upon their return a report was published from information supplied by them wherein it was stated that they had reached Westernport. The mistake was of some importance when in 1826 Governor Darling sent out the expedition to occupy Westernport in suspicion that the French under Dumont D'Urville intended to do so. Messrs. Hume and Hovell had traversed excellent country, and, had their report indicated that it lay to the west of Port Phillip, the expedition of 1826 would undoubtedly have been directed to settle there instead of at Westernport, where, after investigation, the conditions were not deemed to be suitable for permanent occupation. Quite a different verdict would have been returned had the expedition directed more of its attention to Port Phillip. It is very curious to observe how little was known in 1825 of the work of the earlier explorers. When Brisbane received the report of Messrs. Hume and Hovell he wrote to London. 'It is my intention, as soon as I have the means, to send a colonial vessel to Westernport to have it explored, as it seems to have escaped Flinders and others.' The Governor was wholly unaware that the port was discovered by Bass in 1798, and that it had since been thoroughly explored and mapped by Murray, Grant, Barrallier, and Robbins, in the first decade of the century.
Allan Cunningham, not less keen as an explorer than as a botanist, fought his way across the Liverpool Range in 1827, penetrated the Darling Downs, and discovered the Gwydir, the Dumaresq, and the Condamine Rivers. Where did they flow? Between the Condamine in the north and the Goulburn in the south was a distance as great as from the Orkneys to Lands End. Nobody suspected that all the intervening rivers, and some more to the west not yet discovered, belonged to the same riparian scheme. That great discovery had yet to be made.
The problem of the rivers was taken in hand by one of the most heroic and daring of Australian explorers when Captain Charles Sturt applied himself to it in 1828. Sturt had come to the country with his regiment, the 39th (Dorsets) in the previous year, and at once became fascinated by the question of what became of the large streams which Oxley had navigated, and which Hume and Hovell had crossed. It was speculated that they poured their waters into a great inland sea. If that were true, where was that sea? Sturt wrote that he undertook his series of toilsome explorations from 'a wish to contribute to the public good'; 'I should exceedingly regret,' he said, 'if it were thought, I had volunteered hazardous and important undertakings for the love of adventure alone.' The spirit of his work was entirely in accord with that profession.
For three years previously to 1828 Australia had been severely afflicted by drought. Crops failed and stock died for lack of grass and water in districts where there was abundance in normal seasons. If there were well-watered areas in the interior, beyond the zone which had hitherto been examined, it was urgent that they should be found.
Sturt's expedition was therefore equipped by Governor Darling with the view of following up the channel of the Macquarie. It was pursued in a boat as long as there was a sufficient depth of water, and then the explorers started off on horseback, travelling a full month over barren, sun-baked, drought-smitten plains, till suddenly they found themselves on the precipitous banks of a river which gleamed forty feet below them. They had found the Darling. The water in it, to their deep disappointment, was brackish, but there were fortunately occasional pools of drinkable water with which they could refresh themselves and their cattle. The parched beds of the Bogan and the Castlereagh were examined before the party were compelled to beat a retreat back to the Macquarie.
The discovery of the Darling was of capital importance. Though Sturt found it in a drought season, when the water was low and salt, and for considerable stretches the bed was quite dry, yet it was evident that those steep banks, down which the cattle could not safely be taken, sometimes held a great, deep, raging river. Here was a new problem. Whence did this river come? Whither did it go?
In 1829 the intrepid Sturt attacked the river problem at a fresh point. Hume and Hovell had crossed the Murrumbidgee on their overland journey to Port Phillip. The direction of this river's flow and that of the Darling seemed to indicate that the two formed a junction somewhere. The speculation was well founded, and the new journey was to prove itself one of high historical interest.
Sturt left Sydney on November 3, and struck the banks of the Murrumbidgee near Yass on November 23. There it was a rapid, foaming stream, fresh from the snowy mountains to the east. Its banks were followed until the water shallowed into reed-beds. Then Sturt, with undaunted resource and energy, decided to leave. his cattle and stores, put together a whaleboat the planks and parts of which he had brought with him, and set out to explore the further course of the river in it. He selected seven of his party to accompany him, three of them soldiers of his regiment, three convicts, all men upon whose devotion and courage he could implicitly rely. At seven o'clock in the morning on January 7, 1830, commenced the very remarkable voyage which was to prove the junction of the Murrumbidgee and the Darling with the Murray, and was to trace the whole course of that great waterway to the sea.