Long before “EOD” existed as a military speciality, New Zealand’s military explosives experts were already being called to suspicious-device scenes. The Marton bus bombing of 2 June 1932 is one of the earliest clearly documented improvised explosive device (IED) cases in which the military’s technical authority, the Inspecting Ordnance Officer (IOO), was tasked to examine the scene and later give expert evidence in court. In an era without bomb suits, robots, X-ray technology, or a formal Explosive Ordnance Disposal (EOD) trade, the IOO brought a disciplined method: identify the hazard, stabilise the scene, reconstruct what happened, and translate technical facts into plain-English findings for police and the judiciary.
This incident matters for three reasons.
- First, it shows that New Zealand had a recognised explosives authority decades before specialist EOD units existed; the IOO’s independence and metrology-based practice gave courts and commanders confidence.
- Second, it illustrates the civil–military interface in action: Army technical assurance working alongside police to resolve a criminal use of explosives.
- Third, it foreshadows today’s Ammunition Technician, the same assurance logic, later reinforced by doctrine, training pipelines, protective equipment, and inter-agency protocols.
In short, Marton (1932) is a proto-EOD moment. It anchors the lineage from a single specialist inspector applying standards in support of civil law to the modern, team-based EOD capability that safeguards the public from both IEDs and conventional ordnance.
Context: The IOO before EOD
In 1932, the IOO was a single, independent appointment responsible for the safety, proof, and certification of arms, ammunition, and explosives. There were no dedicated bomb-disposal teams, render-safe procedures, or modern PPE. When police needed expertise in explosives, the State turned to the IOO—the most credible technical authority available.
In 1932, the IOO was Major William Ivory, RNZA (1896-1949), an ammunition specialist who served as IOO, Acting Inspector of Ordnance Machinery (IOM), and later as Ordnance Mechanical Engineer (OME). A Graduate of the Royal Military College (RMC) in Australia, Ivory was appointed IOO and Acting IOM on 1 May 1921 after UK training at Woolwich (Inspecting Ordnance Officers’ Course; 36th Advanced Ordnance Course). He served as Acting IOO until 18 June 1925, when he returned to the RNZA to undertake regimental duties. Returned as IOO on 2 January 1927 and retired on 6 April 1933 as IOO/OME. On leaving New Zealand, Ivory continued his career with the British Army.
Widely regarded as the post-WWI technical lead for ammunition and ordnance in New Zealand, Ivory is credited with designing, erecting, and organising the Trentham military workshops, implementing the Mount Cook Barracks demolition scheme, and coordinating NZ-wide military workshops for repair and maintenance, work that shaped the IOO/OME functions for years to come.[1]
The incident
On 2 June 1932, an explosive device damaged a rival bus operating on the Marton–Palmerston North route during a period of hard-fought commercial competition between private carriers. Police quickly focused on Charles William Hoffman, a local proprietor, who was charged with blowing up a rival’s vehicle and possessing an explosive device; he later pleaded guilty.
Surviving summaries indicate a deliberately placed, improvised charge rather than any legitimate blasting operation. The device fits today’s definition of an IED: a non-standard explosive assembly, fabricated from available materials and employed for a criminal purpose. Contemporary accounts emphasise targeted disruption of a competitor’s service rather than indiscriminate harm. While the record available here does not detail injuries, it does point to material damage consistent with a small, locally initiated charge positioned to maximise nuisance and mechanical effect (e.g., underbody or luggage area), rather than a high-yield attempt at mass casualties.
Police secured the scene, recovered fragments and residues, and requested the attendance of the Inspecting Ordnance Officer (IOO) to classify the device and interpret effects. That civil–military handover—police control, ordnance classification—frames the case as an early, well-documented example of New Zealand using independent technical assurance to translate a suspicious explosion into prosecutable facts.[2]
The callout: IOO on scene
The IOO examined the scene and later provided expert evidence. While equipment and doctrine were rudimentary by modern standards, his approach followed a logic that still reads as EOD:
- Identify/classify: determine the nature of the explosive, initiation method, and improvised features.
- Reconstruct: read fragmentation/sooting and container deformation to estimate charge size and placement.
- Control safety: establish a cautious approach, prevent unsafe handling, and confirm no secondary hazards.
- Record for court: translate technical findings into evidential facts.
What this tells us
- The State already knew who to call. IOO = independent, methodical, court-credible.
- Method before gear. The identify → isolate → examine → document sequence predates modern tooling.
- Civil–military interface. Early instance of police–ordnance cooperation that later formalised into EOD arrangements.
- Seed of later trades. Incidents like Marton helped define the problem space that produced ATO/AT and formal EOD capability.
The Marton case stands as a proto-EOD moment: the State’s inspection authority applying disciplined, independent standards to a live improvised-explosive incident in support of civil law. Decades before specialist teams, robots, or X-ray, the Inspecting Ordnance Officer brought hazard identification, scene stabilisation, reconstruction, and evidential reporting to bear—quietly proving that method can outrun technology when it has to.
What followed built on that foundation. As New Zealand formalised Ammunition Technician/ATO and EOD capabilities, it did not invent assurance from scratch; it codified habits already visible in 1932:
- Independence from ownership and operational pressure;
- Metrology and reference standards rather than guesswork;
- Repeatable procedures that travel from bench to scene to courtroom; and
- Evidential rigour that can withstand scrutiny.
The Marton callout, therefore, marks both an endpoint of the single-officer IOO era handling civil explosive crime and a beginning, foreshadowing the team-based, doctrine-driven EOD enterprise that would follow.
Seen in this light, Marton is more than an early IED prosecution. It is a hinge in the lineage of New Zealand’s military ammuntion profession: a case where technical assurance served public safety, strengthened the civil–military interface, and left a template for a small, durable, and recognisable approach to how the country would later confront both IEDs and conventional ordnance with confidence and care.
[1] “Ivory, William “, Personal File, Archives New Zealand 1916-1933, http://ndhadeliver.natlib.govt.nz/delivery/DeliveryManagerServlet?dps_pid=IE20515584.
[2] “Remarkable Evidence,” Wanganui Chronicle, Volume 75, Issue 150, 28 June 1932, https://paperspast.natlib.govt.nz/newspapers/WC19320628.2.74.
