He became a soldier in the British Army and fought in the Napoleonic Wars as a member of the Royal Scots Greys cavalry unit.
Leaving his son behind, James Ainslie traveled to New South Wales, Australia in the ship Admiral Cockburn, arriving in February 1825.
On his way from Bathurst to find an appropriate site for a sheep station, Ainslie and his convict labourers came across a terrified group of Aboriginal Australians near Booroowa.
[3] Ainslie was guided to the south-east by that woman[4] and established Campbell's property, later named Duntroon in the area of present-day Canberra.
With the aid of James Cowan and Duncan Macfarlane, who were overseers from the nearby properties owned by Joshua John Moore and G.T.
Cowan, Ainslie and Macfarlane with the assistance of four local Aboriginal men and several police constables went out to capture the bushrangers dead or alive.
[7] In January 1835, Robert Campbell announced there had been "irregularities and insubordination...occasioned by a [liquor] Store on a neighbouring Farm"[1] and made it known that he would henceforth pay no more orders drawn by Mr Ainslie.