Lieutenant General Sir Alwyn Ragnar Garrett, KBE, CB (12 February 1900 – 4 November 1977) was a senior commander in the Australian Army.

He was adjutant and quartermaster in several regiments of the Australian Light Horse before undertaking staff training in England, which he completed just as the Second World War broke out.

As CGS from March 1958, Garrett focused on rearmament and reorganisation, initiating the Army's short-lived restructure into a "pentropic" formation.

[4] In November 1923, Garrett was seconded to the British Army, and spent the next twelve months attached to the 2nd Dragoon Guards in Bangalore, India.

[3][6] He married Shirley Lorraine Hunter, a nurse, on 9 September at St Peter's Anglican Church in the Adelaide suburb of Glenelg; the couple had a son and a daughter.

[2][13] The brigade departed for the Middle East in May but, owing to the military situation following the Fall of France, it was diverted to Britain, arriving in June.

[2][14] Garrett was promoted lieutenant colonel on 16 September and took command of the 2/31st Battalion the same day; he handed over to Selwyn Porter in February 1941, and departed England for the Middle East.

[2] Returning to Australia, Garrett was promoted to temporary colonel in April 1942 and became senior operations officer in the 1st Armoured Division, which formed a key part of the forces held in reserve to contest a Japanese invasion.

[2][20][21] The campaign was controversial in that it appeared to have little impact on the main drive against Japan; Garrett was quoted as calling it "an absolute waste of time".

[23][24] Garrett was also responsible for interrogating the first Japanese peace envoy to make contact with the Australians on Bougainville, on 18 August 1945, and was present when the instrument of surrender was signed on 8 September.

[2][28] His "exceptional service in the field" in the South West Pacific Area earned him a mention in despatches, which was gazetted on 6 March 1947 and backdated to 2 November 1946.

[39][40] Alan Stretton, executive officer to the Military Board at the time, recalled Garrett's sense of humour and "most informal" manner.

[41] In August, the CGS announced to his senior officers a radical reorganisation of the Army that would strengthen the regular forces and reduce reliance on the CMF, which since Federation had formed the backbone of Australia's military.

This plan included the abolition of National Service, to which the Federal government had already agreed, and the introduction of a "pentropic" divisional structure.

[42] Garrett championed the pentropic structure to overcome what he saw as the weakness of the traditional battalion for overseas deployments, and to ensure compatibility with the US Army's pentomic formations.

[48][49] On retiring from the military, Garrett became principal of the Australian Administrative Staff College, a private institution delivering courses to senior business and government personnel at Mount Eliza, Victoria.

[2][50] During his four-year tenure, he lobbied for the reintroduction of conscription, and when the Federal government brought in a new selective service scheme in 1965, he was invited to draw the first ballot of names.