As Lieutenant Governor of New South Wales he governed the colony from 1792 until 1794, in which he established military rule, abolished civil courts, and made generous land-grants to his officers.

Grose served during the American Revolutionary War, where he was twice wounded (at the assaults on Fort Montgomery and Monmouth Court House).

[1] Grose did not leave England until late in 1791, arriving in Sydney on 14 February 1792 on board the convict transport Pitt.

The voyage was not an easy one as fever killed a large number of people on board, seaman, soldiers, convicts, wives, and children.

In a connived attempt to improve agricultural production and make the colony more self-sufficient, Grose turned away from collective farming and made generous land grants to officers of the Corps.

They were also provided with government-fed and clothed convicts as farm labour, whose products they would sell to the government store at a good profit.

The custom of officers trading in spirits was almost universal and in the interregnum before the arrival of Captain Hunter, the colony was rife with drunkenness, gambling, licentiousness and crime.

[1] In spite of the low state of morality and the drinking habits of the people, the position of the colony had improved very much when Grose left for England on 17 December 1794.