was full of vitriol for Irwin's actions: "It is hard to conceive any offence on the part of the poor unfortunate wretch that could justify the putting him to death, even in the open field, but to slay him in cool blood to us appears a cruel murder without palliation." Irwin, however, was convinced that his actions were merited. Writing in England about two years after the events of 1833, he asserted that 'these acts of justice so completely succeeded in their object of intimidating the natives on the Swan and Canning Rivers that recent accounts from the colony represent the shepherds and others in the habit of going about the country, as having for a considerable laid aside their usual precaution of carrying firearms, so peaceable had the conduct of those tribes become.' In September 1833, after more than four years in Western Australia, Irwin returned to England, partly to give an account to the Colonial Office of the events that had occurred in the colony while it was under his charge. While there, he published The State and Position of Western Australia, the first published account of the colony. He also sought religious assistance for the colony, resulting in the arrival of the colony's first missionary, Louis Giustiniani, in 1836. He married his wife Elizabeth Courthope, sister of auditor-general of Western Australia in December 1836. In 1837, having been promoted to Major, he returned to Western Australia, and was made permanent Commandant of the Western Australian Forces. He was further promoted to Lieutenant-Colonel in 1845. On the death of Governor Andrew Clarke in February 1847, Irwin took office as acting Governor until the arrival of the new governor, Charles Fitzgerald, in August 1848. His administration was extremely unpopular with the settlers of Western Australia, due to both the poor financial state of the colony and his stern character, and the arrival of Fitzgerald was widely celebrated. Irwin retired from the army in 1854 and returned to England in 1856, where he died in Cheltenham in 1860. In 1839 the explorer George Grey named the Irwin River after him while on his second disastrous exploration expedition along the Western Australian coast. In 1948 the Irwin Army Barracks in Karrakatta were named after him, in recognition of his place in Western Australia's military history. In 1991 the Frederick Irwin Anglican School was opened and named in honour of his contributions