A lawyer and part-time soldier prior to the outbreak of World War I, Blackburn enlisted in the Australian Imperial Force in August 1914, and was assigned to the 10th Battalion.

After the outbreak of World War II, Blackburn was appointed to command the 2/3rd Machine Gun Battalion of the Second Australian Imperial Force, and led it during the Syria–Lebanon Campaign against the Vichy French in 1941, during which he personally accepted the surrender of Damascus.

They embarked on SS Ionian on 1 March and a few days later arrived at the port of Mudros on the Greek island of Lemnos in the northeastern Aegean Sea, where they remained aboard for the next seven weeks.

The 3rd Brigade covering force fell well short of its ultimate objective, the crest of a feature later known as "Scrubby Knoll", part of "Third (or Gun) Ridge", but Blackburn and Robin, who were sent ahead as scouts, got beyond it.

[24][a] Held up by heavy machine gun fire and bombs, McCann, who had been wounded in the head, reported to the commanding officer (CO) of the 9th Battalion, Lieutenant Colonel James Robertson, that more help was needed.

[45][75] In September and October 1928, Blackburn helped raise a volunteer force which was used to protect non-union labour in an industrial dispute on the wharves at Port Adelaide and Outer Harbor.

Initially called the "Essential Services Maintenance Volunteers" (ESMV) then the "Citizen's Defence Brigade", the men of this organisation, armed with government-issued rifles and bayonets, were deployed by the South Australia Police to intervene in the dispute between union and non-union labour on the docks.

[59] On 1 July 1939, a few months before the outbreak of World War II, he was promoted to lieutenant colonel and appointed to command the 18th Light Horse (Machine Gun) Regiment.

[90][91] The Allied plan involved four axes of attack, with the 7th Division committed mainly to the coastal drive on Beirut in Lebanon and the central thrusts towards Damascus in Syria.

This involved a blacked-out night-time drive of 28 miles (45 km) at relatively high speed over rough and treacherous roads to the bridge; Blackburn drove in advance of his force.

Late in the day, a battalion of British infantry arrived and, under covering fire from the machine gunners, attacked and captured the town; the 25-pounders knocked out three Vichy French armoured cars.

With the Vichy French stymied in the centre and the Allies unable to press forward from Damascus, the overall commander, now-Lieutenant General Lavarack, decided to put his main effort into the coastal push towards Beirut.

[102] D Company of the 2/3rd, split up among the various infantry battalions pushing up the coast road, fought at Damour in early July,[103] before the Vichy French requested an armistice in mid-July.

[105] At the end of July, Blackburn left the battalion to join the Allied Control Commission for Syria in Beirut, responsible, among other functions, for the repatriation of French prisoners-of-war (POW).

[111] Blackburn, as senior officer on board, was appointed as the commander of the embarked troops, and ensured that the soldiers were kept busy with air raid and lifeboat drills, physical training and lectures.

[112] Blackburn received orders to put 2,000 of his men ashore at Oosthaven on Sumatra in the Dutch East Indies to help defend an airfield near Palembang, about 190 miles (300 km) north of the port.

Due to a lack of small arms, some of the troops were equipped with weapons from Orcades' armoury, including outdated and unfamiliar Springfield, Ross and Martini Henry rifles.

[113] Orcades was escorted across the Sunda Strait, and about 14:00 on 16 February, it anchored in the outer harbour of Tanjung Priok, the port of Batavia, the capital of the Dutch East Indies.

[117] Based on lessons learnt from the fighting in Malaya and Singapore that highlighted the futility of static defence, Blackburn adopted mobility, counter-flanking movements and defence-in-depth as his maxims for Blackforce.

As part of the withdrawal, the Dutch blew up the 260-foot (80 m) bridge over the Tjianten River at Leuwiliang early on 2 March, severely restricting Blackburn's freedom of manoeuvre against the southern force.

Now able to consolidate a position against the southern force, Blackburn disposed two companies of his strongest fighting unit, the 2/2nd Pioneers, in depth along the road just east of Leuwiliang, and kept the remainder of Blackforce in reserve, ready to conduct counter-encirclement operations.

Blackburn, realising that the Japanese would begin to probe his defences and try to outflank them, ordered his reserves to fan out to the north and south of the main blocking position at Leuwiliang.

The food rations at the Bicycle Camp were poor, and because Japan was not a party to the Geneva Convention Relative to the Treatment of Prisoners of War and did not follow its stipulations, it was difficult to maintain discipline as all but Blackburn had to work regardless of rank.

The unit historian of the 2/2nd Pioneers later wrote of Blackburn's time at the Bicycle Camp, "His quiet dignity, masking an unquenchable spirit of protest against Japanese injustices, earned him the admiration of the officers and men who shared with him the humiliation of captivity".

On 7 January a party of 900 POWs arrived from Java, including a large number of 2/3rd men, led by the surgeon Lieutenant Colonel Ernest "Weary" Dunlop.

After a short stay in a camp that held American and Indian POWs, the party of senior officers left Japan by ship on 25 January, and four days later disembarked in southwestern Formosa (now Taiwan).

[140] Blackburn's Second AIF appointment was terminated on 18 July, at which time he relinquished his temporary rank of brigadier and was transferred to the Reserve of Officers List.

[59] On 11 October 1946, Blackburn was again appointed to active duty from the Reserve of Officers List, and was again temporarily promoted to brigadier while he was attached to 2nd Australian War Crimes Section as a witness before the International Military Tribunal for the Far East in Tokyo, Japan.

[152] Blackburn died on 24 November 1960 at Crafers, South Australia, aged 67, from a ruptured aneurism of the common iliac artery, and was buried with full military honours in the AIF section of Adelaide's West Terrace Cemetery.

[153] His medal set, including his VC, was passed to his son Richard, then to his grandson Tom, before being donated to the Australian War Memorial, Canberra, where it is displayed in the Hall of Valour.