The Commanding Officers of Headquarters PIR during this period were as follows:[5] Units of the regiment fought in the campaigns in Papua, New Guinea, New Britain and Bougainville.

[note 1] Despite this reputation there were some incidents of indiscipline—particularly on New Britain during the raising of 2 NGIB—but these were usually related to pay and conditions or perhaps to perceived 'insensitivity' on the part of Australian officers.

[2] During the course of the war more than 3,500 Papuans and New Guineans served in the ranks of the PIR,[2] suffering casualties (both Europeans and natives) of 65 killed, 16 missing, 75 died of other causes, and 81 wounded.

[5] In the years immediately following the war much consideration was given by the Australian Army to re-establishing a presence in Papua New Guinea; however, there was some opposition among white settlers to the raising of native units.

As an interim measure, the re-establishment of the Papua New Guinea Volunteer Rifles (PNGVR) was approved in July 1949, re-forming as a 'whites-only' reserve unit of the Citizen Military Forces (CMF).

[8] It was envisioned that the PIR would have four roles in war-time: garrisoning Manus Island and other similar areas; patrolling the land border with Dutch New Guinea (later Indonesian West Irian); and acting as a delaying force if required; and providing detachments for Australian units deployed to PNG.

[2] In 1960 when the Pentropic division was introduced into the Australian Army, PIR remained the only infantry battalion organised on the old establishment.

[2] During the Indonesia-Malaysia confrontation (1962–66) the regiment patrolled the Indonesia-Papua New Guinea border and although there was only one shooting incident between the PIR and Indonesian troops, a number of incursions took place and these patrols—which were often conducted in rugged terrain—placed considerable demands on Australia's already limited defence resources.

[11] Amid growing Australian concern about Indonesian intentions the PIR began training for guerilla operations, and in September 1963 a second battalion was authorised, subsequently being raised in 1965.

[13] In 1970, Prime Minister John Gorton sought to call out the PIR to keep the peace on the Gazelle Peninsula, where the separatist Mataungan Association was illegally occupying land.

[15] Currently, the regiment consists of two battalions: Units of RPIR were deployed to Vanuatu in 1980 to put down a secessionist revolt there, and were again called out in aid of the civil power in Port Moresby in 1983.

[16] More recently, following the passage of a constitutional amendment allowing the stationing of the PNGDF on foreign soil, 80 personnel joined the Australian-led Regional Assistance Mission to the Solomon Islands (RAMSI) in July 2003.

PNGDF troops continued to serve in the Solomon Islands as part of the scaled down, rotational Pacific contingent until the military component of RAMSI was withdrawn in 2013.