The Castle Forbes was built at Aberdeen in 1818.  This was the second of two voyages bringing convicts to Australia, the first being in 1820.
The convicts came from counties in Ireland. Some had been convicted of offences under the Insurrection Act.....
Limerick 5th July 1823...The following were convicted on the clearest of evidence....James Keefe, from the county Cork and could not account why he was found at Cappa, where several outrages have been committed. Edmond Burke and Edmond James Burke, for tendering an unlawful oath to Edmond McNamara, of Clonoul, near Cappa, whose house was since consumed by the insurgents. Patrick Nash, Thomas Nash, John Kilroy, Michael Hartney, John Fitzgerald, and Thomas Carmody, for being absent from their dwellings.
It appeared in evidence, that they were concerned in attacking John King's house at Ballyalline, on the 17th May and cruelly flogging the inmates and destroying their furniture. The foregoing were sentenced to seven years transportation and were instantly dispatched on their route to Cork, attended by the bitter lamentations of their friends. 
The Castle Forbes departed Cork 28th September 1823.
The Guard comprised a detachment of the 40th under orders of Lieut. John Richardson which including the women and children amounted to 56 persons. Lieutenant-Colonel William Balfour of the 40th regiment also arrived on the Castle Forbes. The 40th regiment had been serving in Ireland.
Early in March 1823, the commanding officer, Lieutenant-Colonel Thornton received an intimation that it was intended to send the regiment to New South Wales. In the meantime it was ordered to proceed to Dublin, thence by sea to Liverpool, and after that by road to Chatham, in order to form guards for convict ships when required.;
The head quarters reached Dublin on 15th March and occupied the Royal Barracks. On the 30th the whole regiment embarked at Pigeon House, in eight small vessels, and reached Liverpool the following day.
A twenty eight days' march, including three Sundays, brought the regiment to Chatham. The Regiment marched in three divisions; the first arrived at Chatham on 21st April; the second, consisting of two companies, halted, and remained at Deptford; and the 3rd reached Chatham on 23rd April.
During the next year the 40th was sent out, in small detachments, as guards on board convict ships to Australia. This was after several years' rough service in Ireland, and but a short period of rest in England........
Embarked 25th April 1823 on ship Albion. Lieutenant Lowe
Embarked 5th July 1823 on ship Asia Captain Bishop
Embarked 10th July 1823 on ship Isabella. Lieutenant Millar
Embarked 18th July 1823 on ship Sir Godfrey Wilestoe. Captain Hibbert
Embarked 29 July 1823 on ship Guildford. Captain Thornhill
Embarked 31st July 1823 on ship Medina. Lieutenant Ganning
Embarked 5 August 1823 on ship Castle Forbes. Lt.- Col. Balfour
Embarked 29 December 1823 on ship Prince Regent. Captain Stewart
Embarked 5th February 1824 on ship Chapman. Captain Jebb
Embarked 25 February 1824 on ship Countess of Harcourt. Captain Morow
Embarked 14 June 1824 on ship Mangles. Lt.- Col Thornton
Embarked 14 June 1824 on ship Princess Charlotte. Lieut Neilley
Other ships bringing detachments of the 40th regiment included the Minerva and Ann and Amelia.
Surgeon Matthew Anderson
Matthew Anderson kept a Medical Journal from 29 July 1823 to 19 January 1824. The chief cause of complaint amongst the convicts was diarrhoea and dysentery. There were a few cases of scurvy which the surgeon treated with lemon Juice and sugar. 
The Castle Forbes arrived in Port Jackson on 19th January 1824, a voyage of 109 days. One hundred and thirty-nine male prisoners were landed, one prisoner having died on the passage - Martin Cavenagh had been severely beaten while in the Depot at Cork which the surgeon considered contributed to his death.
Matthew Anderson was also surgeon on the Surry in 1819, Mangles in 1820 and the Mangles in 1822
Notes and Links
1). Convict Michael Halpin was on a Colonial Office list of thirteen people who applied for their families sent to New South Wales.........
2). Find about bushranger Patrick Riley who arrived on the Castle Forbes
7). Return of Convicts of the Castle Forbes assigned between 1st January 1832 and 31st March 1832 (Sydney Gazette 5 July 1832)..... Edward Reardon. Indoor servant assigned to Henry Drinkwater at Sydney