Garrett Armstrong arrived on the Recovery as a soldier of the New South Wales Corps in 1808.  The Recovery left Rio at the beginning of May in company with the Lady Sinclair, however parted soon afterwards in a gale of wind.

The Sydney Gazette reported that the Recovery arrived off Sydney Heads on Saturday 23rd July 1808 with 119 troops of the New South Wales Corps. Captain Cummings of the NSW Corps landed that same evening with the Naval Officers. The troops were reported to be in good health and spirits.

Garrett Armstrong was court-martialled for desertion in June 1809 -

At a General Court Martial held at Sydney on 16th June, of which Major Abbott of the New South Wales Corps was President, was tried Garrett Armstrong, Private Soldier in His majesty's New South Wales corps charged with having deserted from the said Corps, and not having returned until brought back by a Party; of which charge he was found Guilty and sentenced to be transported as a Felon, and to serve as a convict in NSW or its dependences during the Term of his natural Life

In January 1810 he was released from Sydney Gaol on the occasion of Lachlan Macquarie taking over as Governor. In June 1810 he was found guilty of forgery and received a sentence of death which was commuted. In November 1810 he absconded from the gaol gang in Sydney and the following March he absconded from Lane Cove after receiving and selling 8 men's rations from the Public Store

He was sent to Newcastle soon afterwards..  By September 1811 he had absconded from Newcastle, this time with two notorious bolters John McCabe and John Fitzgerald. They were believed to be lurking about the lower Hawkesbury region and inhabitants were cautioned against harbouring or employing them on pain of prosecution. They were apprehended at sent back to Newcastle. He absconded again in November 1812 probably with William Harrison Craig. They were captured and punished with 25 lashes each. He was at Newcastle at the same time as James Hardy Vaux.

Lieutenant Skottowe was Commandant at the settlement.

Garrett Armstrong absconded from Newcastle in 1814 and was sent back a week later.

In 1819, still a prisoner, he was sent to Van Diemen's Land on the Prince Leopold to work in public service and was granted a Ticket of Leave in Hobart in 1835.

Garrett Armstrong died 1st February 1836 at Launceston, Tasmania.