In 1823, Sturt was gazetted Lieutenant, and his promotion to Captain followed in 1825.
In December, 1826, he sailed for New South Wales with a detachment of his regiment, in charge of convicts.

The moment he set foot on this vast unknown land, its chief geographical enigma at once occupied his attention.

Sir Ralph Darling, to whom he acted for some time as private secretary, formed a high opinion of his tact and ability, and appointed him Major of Brigade and Military Secretary.
6.2.THE DARLING.
As soon as an expedition inland was mooted, Sturt volunteered for the leadership, and was recommended by Oxley, who was then on his deathbed.
The recommendation was adopted by Governor Darling, and Sturt embarked on the career of exploration that was to render his name immortal.
It was ever Sturt's misfortune to be the sport of the seasons; drought and its attendant desolation dogged his footsteps like an evil genius.
Oxley had followed, or attempted to follow, the rivers down when a long period of recurrent wet seasons had saturated the soil, filled the swamps and marshes, and swollen the river-courses so that they appeared to be navigable throughout for boats.

Sturt came at a period when the country lay faint under a prolonged drought and the rivers had dwindled down into dry channels, with here and there a parched and meagre water-hole.

The following description of his is too often quoted as depicting the usual state of the Australian interior:-- "In the creeks, weeds had grown and withered, and grown again; and young saplings were now rising in their beds, nourished by the moisture that still remained; but the large forest trees were drooping, and many were dead.