A naval officer friend of the family, Captain Charles James Tyers, suggested that if Kennedy obtained the necessary qualifications, he would arrange employment for him in Australia.

Another family contact Captain Perry, who was deputy to Sir Thomas Mitchell, arranged a position for Kennedy as assistant surveyor in the New South Wales Survey Department after he had passed an examination.

Kennedy received praise from Mitchell for his work in Portland and remained employed in the government surveying department in Sydney, but at half-pay.

Kennedy in a letter to his father noted that the party consisted of 30 men, 12 months supplies plus "8 drays, 3 carts, 102 bullocks, 255 sheep, [and]17 horses.

To allow time for stock to refresh, he left Kennedy at a depot camp for three weeks, thereafter to follow slowly while Mitchell probed northwards with a small party.

Mitchell continued to follow the Balonne, which took him too far north-east, so he veered west until coming across the Maranoa River where Kennedy and the main party caught up on 1 June 1846.

At least four streams, the Nogoa, Belyando, Nive and Nivelle were traced to determine their direction of flow, but none trended north-west, and much time was employed in so doing.

[3] Mitchell was impressed with the leadership qualities of Kennedy, as demonstrated by his management of the depot camps in 1846, and his technical skills relating to survey and exploration.

Kennedy had spent some time plotting Mitchell's Victoria river on the latest map of the colony, and was struck by the fact that its general course turned towards a bend of Cooper Creek, named by Charles Sturt in 1845.

Kennedy decided to conceal the carts and supplies from local aborigines by digging a large trench in which to bury them, then proceeded by packhorse.

[2] The country began to deteriorate and by early September Kennedy was forced to retreat to his hidden cache because of lack of water and supplies.

He further suggested that after a resupply of the party at the tip of the cape, the exploration could continue down the west coast, with a subsequent return overland to Sydney.

This idea was accepted, and planning began for Kennedy to head for a starting point at Rockingham Bay, near the present town of Cardwell, Queensland.

[2] On 28 April 1848 Edmund Kennedy and twelve men sailed from Sydney Harbour[1] in the barque Tam O' Shanter escorted by Rattlesnake.

[Note 1] They arrived at Rockingham Bay 20 May, but once they had landed, the party encountered terrible terrain such as mangrove swamps, mountains, lagoons, rivers, and thick rainforest that made it almost impossible to travel with horses, carts, and sheep.

Days after crossing the Pascoe River, when in the vicinity of Shelburne Bay, Costigan accidentally shot himself while tending his horse and could not continue, so Luff and Dunn were left behind to care for him.

[7] During his life and career in Australia, Kennedy maintained an overtly negative view of the Indigenous people, writing that: "I sincerely trust they will soon be exterminated...they are a barbarous set of rascals never to be tamed.

[11][12] On 11 November 1948 a monument to Kennedy was erected at Portland Road (Weymouth Bay) in Iron Range in Queensland near a spring where the expedition drew water.