In August, 1801, he had been appointed by Governor King military engineer, in place of Captain Abbott resigned.

In February, 1802, he was succeeded by Lieutenant George Bellasis, an artillery officer.

Besides his expeditions to the Blue Mountains, he did much surveying with Lieutenant James Grant in the Lady Nelson.

In 1804, he went to England and saw service in several regiments, distinguishing himself greatly in military engineering, amongst his works being the erection of the Nelson Column in Trafalgar Square, the designer of which was Mr.Railton.Barallier died in 1853.
Peron, the French naturalist, tells us that when in Sydney in October, 1802, he persuaded Governor King to fit out a party to attempt the passage of the mountains, and that a young Frenchman, aide-de-camp to the Governor, was intrusted with the leadership.

He returned, however, without having been able to penetrate further than his English predecessors.
On the following month, however, Barallier set out from Parramatta, on his famous embassy to the King of the Mountains.