31/51st Australian Infantry Battalion

Battle Honours
Campaign Honours
Commanding Officers
Decorations 1 DSO; 1 DCM; 3 MC; 10 MM; 1 BEM; 27 MID
Conflict Second World War, 1939-1945
  • AWM52/8/3/70: 31 Battalion and 31/51 Battalion war diary
  • AWM52/8/3/89: 51 Battalion war diary
  • Burla, Robert, Crossed boomerangs : the history of all the 31 Battalions(Loftus [N.S.W.] : Australian Military History Publications, 2005)
  • Davidson, Audrey, Porton : a deadly trap : the facts about the Battle of Porton Plantation, Bougainville 1945(Moorooka, Qld. : Boolarong Press, 2005.)
  • Hughes, William E, At war with the 51st Infantry Battalion and 31/51st Infantry Battalion (AIF) from 1940 to 1946(Brisbane : Church Archivist Press, 1993., 1993)
  • James, Karl, "Hell at Porton"
Category Unit
Conflict Second World War, 1939-1945
Unit hierarchy

After the First World War the defence of the Australian mainland lay with the part time soldiers of the CMF - otherwise know as the Militia. The Militia was organized to maintain the structure of the First AIF and kept the same numerical designations. These Militia units were also distributed in the same areas that had raised the original AIF units. Consequently, Militia units were also known by the name of their shire. Thus, Townsville's 31st Infantry Battalion was the "Kennedy Regiment", while the 51st Infantry Battalion was the "Far North Queensland Regiment". The 31st and 51st were both raised in 1921, however during the 1930s little was spent on defence and the Militia had few volunteers. The 51st merged with the 30th Infantry Battalion and then the 18th Infantry Battalion in 1935. The following year the two were unlinked.

Following the start of the war, in early 1940, the 11th Brigade, then composed of the 26th, 31st, and 51st Battalions, went into camp at Miowera near Bowen, on Queensland's north coast. The 31st and 51st received their first intake of men called-up for national service. The 31st drew its personnel from and around Townsville, Home Hill, Ayr, Bowen, Charters Towers, and Ingham. Similarly, the 51st drew its personnel from and around Cairns, the Atherton Tablelands, Mossman, Innisfail, and Tully. These districts were all sugar-growing areas and many of the men came from Italian families. Consequently, in June when Italy entered the Second World War on the side of the Axis, the 26th was sent to Kissing Point near Townsville, to deter to any possible unrest.

In early 1942 the 11th Brigade, with is headquarters in Townsville, was allocated the defence of Far North Queensland. The 31st was allocated to Townsville, the 26th went to Charters Towers, and the 51st to Cairns. In March the 51st was relocated to Sellheim near Charters Towers. Townsville though was becoming increasingly important as a navel base and in April the 51st moved to Townsville. There were several Japanese air raids on the town and harbour while the brigade was in Townsville.

With the threat of a possible Japanese landing, the 31st was sent to Jacky Jacky, at the top of Cape York Peninsula, in August. The 31st was in command of a small force called York Force, which was disbanded shortly after Christmas 1942. Meanwhile, with the 31st located north, it was believed that the 51st would also go overseas. However, it went to Cairns instead.

In order to meet the needs of the ever-growing war economy, in February 1943 the Federal Government released the men who had worked in essential industries from the army. When the rural workers were discharged the 31st and 51st became severely depleted. Hence, on 12 April the two battalions were merged, forming the 31st/51st Infantry Battalion.

In mid-1943, while still in the Cairns area, the 31st/51st underwent amphibious training, using American landing craft. But it was going to be some time before the battalion could put what it learnt into practice. Leaving Australia in June, the battalion travelled to Merauke in Dutch New Guinea, via Horn Island in the Torres Strait, arriving in July. Merauke Force was comprised of units mostly from the 11th Brigade. Consequently, the 11th Brigade had the distinction of being the only Militia unit to have served outside Commonwealth territory.

In August 1944 the brigade was withdrawn from Dutch New Guinea and the 31st/51st travelled via Thursday Island to Townsville, for some well-appreciated leave. The battalion, along with the rest of the brigade, then assembled at Strathpine for training, in preparation for its next deployment - Bougainville. Until now the 11th had spent the war doing garrison duties; but this was about to change.

In December the 11th Brigade, now the 26th, 31st/51st, and 55th/53rd Battalions, moved to Bougainville. The brigade was responsible for the Northern and Central Sectors.

From December 1944 until February 1945, the 31st/51st advanced along Bougainville's north-east coast. Despite occupying Amun, Sipaai, and a number of other villages, the Australians did not meet any major Japanese resistance until the battalion reached the Genga River. Here, at Tsimba Ridge, the Japanese had dug in and heavily fortified their position. After 21 days, from 17 January to 9 February, of continuous fighting the Japanese finally abandoned the ridge. The 31st/51st crossed the Genga and patrols moved inland, establishing a position at New Newborose, later named Downs' Ridge. The 31st/51st was then relieved by the 26th, which continued the advance north.

At the end of May the 31st/51st joined the 26th, which had relieved the 55th/53rd, in maintaining the Ratsua-Ruri Bay line. Following the 26th's successful use of amphibious landings to clear the Soraken Peninsula, the 31st/51st planned to land a company at the coconut plantation at Porton. This company would then link up with the rest of the 31st/51st and the 26th would move north from the Ratsua-Ruri line. The landing at Porton took place during the night of 7 June but the company, under the command of Captain Henry Clyde Downs, soon ran into trouble. They were quickly surrounded by the Japanese, while the rest of the 31st/51st and 26th could not penetrate the enemy's lines fast enough. Downs's ill-fated company had to be evacuated by sea, in which they also ran into trouble. The rescuing landing craft were overcrowded and ran aground. The last group of standard Australians were not rescued until 11 June. This second campaign in the Northern Sector was a "short, but bloody one", concluded the 31st/51st's official history. From 4 to 28 June the battalion suffered 100 casualties, including 14 killed, seven missing, and 79 wounded. The battalion killed 179 Japanese and another 53 were believed killed. The 11th Brigade was relieved by the 23 rd Brigade at the end of June.

In September, after Japan's surrender, the 31st/51st was transferred to Nauru and Ocean Islands, as part of the occupation force that garrisoned the islands. Beginning in October the Japanese were transported to Torokina and then Fauro Island for repatriation to Japan. The occupation force stayed in the islands until December, when the 31st/51st was transferred to Rabaul in New Britain where it performed a similar role. The battalion stayed on Rabaul until May 1946 when it finally returned to Australia. The 31st/51st was disbanded on 4 July 1946.