He survived Kennedy's fatal 1848 expedition into Cape York Peninsula (in present-day Queensland) and was subsequently formally recognized for heroic deeds by the Colony of New South Wales in words engraved on a solid silver breastplate or gorget,[5] which read as follows:[5] Presented by His Excellency Sir Charles Augustus FitzRoy K.D.

[2]As a young man, Galmahra seems to have grown up and lived at Jerrys Plains near Muswellbrook, New South Wales, most likely as a member of the local Australian Aboriginal nation:[8] the Wonnarua.

[9] In April 1848, still a young man, Galmahra was asked to accompany and help guide Assistant Surveyor Edmund Kennedy and team (including botanist William Carron[10][11]) on an expedition through unknown country heading up into Cape York Peninsula.

[12] By March 1849 a lithographic portrait of 'Jackey Jackey' had been produced for sale,[13] and by the beginning of 1851 the Governor of New South Wales had presented him with a specially made, pure silver breastplate (see above) plus a £50 bank account gratuity.

Instead he gained a reputation for enjoying his alcohol and, in 1854, after drinking too much during an overland journey to Albury, New South Wales, fell into a campfire and died.