This article is central to the Engineer Capability Review ‘23. There is an upcoming Mission Analysis for the review at the Corps Conference over the period 31 Oct – 4 Nov ’22.

Today, the principles of employing engineers are rarely, if at all, applied above brigade-level in the Australian Army. Is this because the principles are irrelevant above the tactical level or because they are not well known? Army engineers, more traditionally called military engineers or Sappers, are a low-density, high-demand, multi-disciplinary technical capability who are employed to achieve effects at the tactical through to strategic levels.

Field Marshal Montgomery is widely quoted to have said, ‘… in the late war there were never enough Sappers at any time’.[1] This view that there are never enough military engineers is shown to be a truism on a regular basis at all levels in the Australian Army and is the fundamental basis for the principles of employment.

This article will firstly define military engineers and their role in the Australian Army before briefly examining the seven principles of employment to evaluate their applicability above brigade-level. The doctrine and practices of our allies, in particular the U.S. Army, United States Marine Corps (USMC) and the Royal Engineers, will be used in comparison with the Corps of Royal Australian Engineers.

This is because our allied engineers provide commensurate capabilities and have similar doctrine, and the structure of the formations to which they provide military engineering are also like the Australian Army.

Sappers working on a buildings construction.

Who are the Sappers?

The Royal Australian Engineers (RAE) ‘enable the Joint force to live, move, fight and win the Nation’s wars'. The corps ‘provides engineering effects to the combined arms teams and specialist engineering support enabling manoeuvre and survivability'.[2] Sappers operate as both multi-disciplinary and specialist engineer units within Army brigades and provide force-level engineering support at the division-level and above.

The RAE also provide specialist engineer capability bricks to other areas of Defence, such as the Security and Estate Group for the delivery of domestic infrastructure and International Policy Division through both the Defence Cooperation Program and the Indo-Pacific Enhanced Engagement Program.

Significant contributions to Campaigning in Competition[3] are made by military engineers. In the past decade, Army engineers have regularly deployed their highly valued capabilities domestically and overseas to deliver a wide range of effects in support of the Joint force as well as to various Government emergency responses. Everyone wants engineers; however, this means they are often overstretched.

The Army’s engineers are a finite resource, and warfighting requires military engineers to undertake a very broad range of tasks and skillsets. At the extreme end of the scale, engineers may be required to breach a minefield during an advance in contact or decontaminate the force in a chemical, biological or radiological environment.

At the other end of the warfighting scale, they might rebuild a school or dispose of explosive remnants of war to assist the local population to return to prosperity after a conflict.[4] To achieve their diverse range of tasks, engineers include a wide range of qualifications and trades aligned to combat and construction engineering – areas that are interdependent and often intertwined.[5]

Combat engineering includes the trades Combat Engineer, Explosive Ordnance Disposal Technician, Explosive Detection Dog Handler and the new Operator Engineer Vehicles but also includes qualification such as Army Work Diver, demolitions supervisor, high-risk search advisor, mine warfare instructor, water purification unit operator, watercraft operator and bridging supervisor. Two related trades are Combat Rescue and Special Operations Engineer.

The construction engineering trades include Carpenter, Electrician, Plumber, Surveyor, Draftsman, Plant Operator, Works Supervisor and Civil Engineer (with similar construction trades in the Air Force). It should be noted Combat Engineers are also skilled labourers who can be employed on construction tasks under the supervision of construction engineers. All military engineers are soldiers first, Sappers second and specialists third.[6]

Sappers holding a flag underwater.

An evaluation of the principles of employment of engineers

Principles are a ‘fundamental doctrine or tenet’ or ‘the method of formation, operation or procedure exhibited in a given case’.[7] As for the principles of war, principles are ‘not laws such as the laws of natural science, where the observance of certain conditions produces a predictable result. Nor are they like the rules of a game, the breach of which entails a definite fixed penalty’.[8]

Principles of war, as a ‘diverse blending of thought’, are a ‘guide to action concerning the employment of combat power [and fighting power], the application of which ‘does not guarantee success’ and ‘circumstances will dictate the relative importance of each principle’.[9] Likewise, the principles of employment of engineers are a starting point to plan military engineer tasks and activities – and generate engineer capabilities – but should be adjusted to the circumstances at hand. The principles of employing engineers ‘complement the principles of war and the tenets of manoeuvre and assist a commander to integrate engineer support into the manoeuvre plan’[10].

Principle 1 – Centralised control with decentralised execution. The predominant principle, the application of which enables the remaining principles to be effectively applied, ensures the most effective and efficient employment of limited resources. The most efficient engineer effects are ‘achieved using centralised control at the highest appropriate level, with responsibility for tactical execution decentralised and delegated to the lowest practical level’.[11] This principle is echoed in British doctrine through their engineer planning factors ‘single point of engineer advice’ and ‘centralised coordination decentralised execution’. The later states ‘command is maintained at the highest appropriate level to enable effective task organisation, though execution of tasks is delegated to the lowest possible level'.[12]

Centralised control with decentralised execution supports the mission command philosophy. The centralised control provides the engineer commander’s intent (to meet the supported manoeuvre commander’s intent) and the resources, while the decentralised execution enables the lowest possible engineer commander to execute the mission within the intent and limitations provided.[13] Mission command is a key tenet of manoeuvre and is fundamental to how command and control is practiced in the Australian Army.

This fundamental principle is achieved in similar ways by both the U.S. Army and British Army, as well as in their respective Joint operational organisations. In the U.S. Army, engineer headquarters command and control subordinate elements. For echelons above brigade, each manoeuvre headquarters has a specialist staff that assists the manoeuvre commander to command and control engineer organisations.[14]

This function can be provided by the senior engineer unit headquarters, as the Combat Engineer Regiment does in an Australian brigade, or by a dedicated engineer staff. An engineer staff in a U.S. Army divisional or major Joint force headquarters is most often found as a subordinate cell within an operations (G3/J3) directorate, although it can be a separate directorate or located in a logistics (G4/J4) directorate. The later would occur when engineer effort ‘predominantly supports sustainment of the joint force’.[15] While the U.S. Army has a large engineer capability at all echelons, they still apply a centralised control model to achieve engineer effects most effectively.

Similarly, the USMC employs an engineer staff in their Marine Air Ground Task Force (MAGTF) command elements. The MAGTF is a task-organised, combined-arms organisations that can be created at the unit, brigade, division and corps (Marine Expeditionary Force) level.[16]

The staff engineers in a MAGTF headquarters ‘develop engineer policy, guidance, and standards for the engineer effort’ throughout the [operating environment] and are the ‘focal point for planning, monitoring, and coordinating engineer efforts supporting air, ground, and combat service support operations and providing engineer assistance to the principal staffs.’ This focus for controlling engineer effects across the operating environment shows the USMC adhere to the predominant principle at all levels.

In the British Army, which does not have the same volume of engineer units at the theatre level as the U.S. Army, centralised control at the highest level is also a feature of engineer command and control. Under the Army 2020 reorganisations, engineer units above the brigade were brought together under the 8th Engineer Brigade as part of Force Troops Command.[17]

Headquarters 8th Engineer Brigade provides the central control and coordination function. Under the subsequent Field Army Restructuring 2019, the 8th Engineer Brigade become the 1st (UK) Division engineers and 25th (Close Support) Engineer Group became the 3rd (UK) Division engineers.[18] Commander 8th Engineer Brigade is also the Chief Royal Engineer Field Army and the standing Joint Force Engineer for Permanent Joint Headquarters.[19]

In addition to coordinating engineer effort for the field forces, the Royal Engineers also apply this principle for the management of their military engineer capability. From 1941 until 2012, the professional head of the Corps of Royal Engineers was the Engineer-in-Chief (Army) who, as ‘Director of Royal Engineers’, was the engineer advisor to their Chief of the General Staff (CGS, their Chief of Army).

This role was also responsible for advising across the Armed Forces and British Government on matters of military engineering on behalf of the CGS. This post was disestablished during the Army 2020 reorganisations and responsibility for the Engineer-in-Chief’s duties were split between the Commandant [Brigadier] Royal School of Military Engineering (for heritage and training), Commander 8th Engineer Brigade (for force generation matters) and the Corps Colonel Royal Engineers (for manning matters and as the first point of contact with external agencies).[20] The British Army has a single voice (albeit through three mouths) for all matters of military engineering from the tactical to the strategic and, thereby, adheres to the principle of centralised control with decentralised execution.

Despite the wide range of tasks, skills, trades and qualifications needed by the RAE to undertake their supporting role across Army and the Joint Force, the RAE is the only technical corps in the Australian Army that does not have a Senior Officer with technical authority who is responsible and accountable for the day-to-day management and employment of the military engineer capability.

For example, there is a G6 Colonel Communications and Information Systems (CIS) function for Signals in Headquarters Forces Command and soon to be established Fires Brigade for Artillery. When Land Command provided the operational land component function for the Australian Defence Force (ADF), the RAE had a Colonel fill the role of Commander Land Command Engineers with a supporting staff. The dedicated engineer authority was abolished in 2006 when some of the functions were absorbed into the Land Command Support Group. The latter was also disestablished after Land Command was merged with Training Command to form Forces Command in 2009.

In 2012, as part of the Modular Engineer Force[21], Force Engineer Branch was created at the direction of then Head Modernisation and Strategic Planning – Army[22] with a Colonel Force Engineer. The mission of the branch was to ‘Provide technical engineer planning advice on all Army engineer capabilities, and act as the focal point for all army engineer matters in order to support the conduct of operations and the [raise, train and sustain] of engineer capabilities.’[23] The Force Engineer and their branch was disestablished in 2019 and has left the Australian Army without a senior technical authority or unified engineer coordination organisation above the unit level; such functions are ‘extra regimental appointments’ for several engineer commanders.

While the principle of centralised control and decentralised execution is applicable above brigade, it is not applied in the Australian Army. This has resulted in incoherent (and sometimes incorrect, such as combat engineers cannot provide construction effects) advice being provided on capability development, force generation and operational employment. By not apply this principle, military engineers in the Australian Army are not always optimally or effectively employed and lack coherency in technical control, application and capability development.

Principle 2 – Early warning and reconnaissance. Military engineering tasks, whether combat or construction related, generally require the ‘relocation and/or assembly of vehicles, equipment, explosives, construction materials and personnel. Moving plant, bridging equipment and construction materials may take considerable time and requires the provision and coordination of external lift capability.’[24]

This remains the case for activities undertaken outside of a brigade’s traditional area of operations, as in Campaigning in Competition when construction effects are required in the remote outback of Australia or on even more remote islands in the Pacific to directly achieve Government directed outcomes.

Early warning and reconnaissance, and the associated skills of anticipation and foresight, are crucial factors in the efficient and effective application of engineer support at all levels.[25] USMC doctrine states ‘engineer reconnaissance is vital to successful MAGTF operations'.[26] This principle and the necessary skills needed to apply it require technically qualified and experienced engineer staff. Such staff should support a commander to ensure the right type of engineers are ‘given maximum possible warning of future activities and likely support tasks’, are ‘involved in the planning process as early as possible’ and are ‘afforded the opportunity to undertake engineer reconnaissance’.[27] Both in times of Campaigning in Competition and times of conflict, this principle is applicable at all levels within the Australian Army.

Principle 3 – Priority of work. British doctrine notes (and reinforces Montgomery’s observation) there are seldom enough military engineers to carry out all allocated tasks simultaneously and commanders must ‘allocate priorities of work’.[28] Likewise, U.S. doctrine states ‘in planning at every level, the engineer planner should … consider … the establishment of priorities … to determine how much engineer effort is devoted to a single task.’[29] The Australian Army has a lower density of combat and general support engineers at every level than both the British and U.S. armies making the issue of insufficient engineer resources even more pronounced. As such, prioritising engineer work is a valid principle at all levels.

As advised in Australian doctrine, the ‘engineer commander must maintain close liaison with the manoeuvre commander and staff to advise on what is achievable, when and by whom, and assist the commander to set priorities for engineer effort.’[30] Without an engineer commander or engineer staff above the brigade level, this principle is not always applied in the Australian Army. This has seen engineer support to higher level tasks applied on a first-come-first-served basis rather than on priority basis.

Principle 4 – Concentration of effort. This principle logically flows from prioritising engineer work and derives from the limited availability of engineer resources. Greater efficiency is obtained by focusing military engineer effort on high-priority support tasks rather than dispersing engineer resources over a larger number of tasks.[31] British Army doctrine notes ‘concentrated engineer forces generally produce the best results; the tendency to ‘penny packet’ resources is wasteful and should be resisted.’[32] Engineer resources, in terms of personnel, equipment and materials, will be calculated by engineer planners to achieve the commander’s intent in the designated time needed. The required resourcing levels should be allocated as per the engineer plan according to the commander’s priorities.

Poor application of this principle above the brigade-level can see military engineers, particularly construction engineers, allocated too thinly to tasks that then extend in duration. This can then see engineers needing to redeploy to complete tasks instead of undertaking refit, reconstitution and training activities. A single source of engineer advice at the highest practical level should ensure adequate resourcing and make recommendations as to the acceptance or non-acceptance of tasks. There is currently no senior engineer responsible for providing such advice.

Concentration of engineer staff effort should also be attempted where practicable. Spreading engineer staff across commands and staff directorates also leads to sub-optimal results. Engineer planners work best as teams, as no one engineer usually has the required qualifications and experience to plan every engineer task in detail or provide advice for every problem needing military engineer support. Engineer staffs should be concentrated under a senior engineer advisor and from a concentrated staff cell provide engineer advice and planning support to the various command, intelligence, operations, logistics and capability development staffs.

Principle 5 – Continuity of effort. Once military engineers have begun work, the same engineer force element should complete the task. Unnecessary redeployment of engineer capabilities and resources must be avoided. Any break in the continuity of work causes delay and usually requires extra engineer effort to complete the task.[33] This principle is even more important above the brigade-level, as the distance for deployment and redeployment is far greater (especially Campaigning in Competition) and often requires strategic lift assets.

Principle 6 – Economy of effort. Military engineers are trained and equipped to undertake an extensive range of technical tasks. Each trade and/or qualification is responsible for multiple tasks with engineers required to rapidly transition from one to another in accordance with the commander’s priorities. It is uneconomical to employ military engineers on tasks that can be conducted by other units. Similarly, and flowing from the principle of concentration of effort, it is also uneconomical to apply more engineer effort than is necessary to complete tasks in the required time or to use engineer effort on the unskilled aspects of military engineering tasks.[34] This principle aligns with the principle of war of the same title.

At the brigade-level, military engineer support primarily focuses on combat engineering effects that enable manoeuvre forces to move, fight and survive. Above the brigade-level, military engineers predominantly provide construction and general engineering effects. The Australian Army has extremely limited capacity for such tasks – the 6th Engineer Support Regiment which has gradually shrunk over the past 15 years, the stretched 19th Chief Engineer Works and newly re-raised 12th Chief Engineer Works. Frequently military engineers from the Combat Engineer Regiments and Reserve Engineer Regiments are required to reinforce.

There are insufficient engineers to provide the needed engineer effects at the operational and strategic levels and using such forces for tasks other than those that require specialist engineer skills can result in tasks being delayed or not achieved. Economy of effort is a relevant principle.

Principle 7 – Protection. This final principle flows from principle 6, in that the employment of military engineers on tasks that can be undertaken by other units is uneconomical. While the secondary role of engineers is to fight as infantry, this is because within brigades they are employed alongside or even in front of combat forces.[35] Military engineers cannot work efficiently and provide for their own protection with such application delaying the completion of engineer tasks.[36] The security situation will dictate the threat and the level of protection required when both Campaigning in Competition and when in conflict. If protection is necessary above the brigade-level this principle is relevant to ensuring limited engineer resources focus on the military engineering effects directed by the commander.

A tank in the bush.


The principles of employing military engineers are relevant above brigade-level. This deduction is based both on how our allies – especially the British Army, USMC and U.S. Army – employ their military engineers as well as through recent experiences of the Australian Army at the operational and strategic levels. While applicable, these principles are not well applied, to the detriment of both the higher commanders’ intent and the health of the Corps of RAE. It is judged this is because the principles are not well known and the Australian Army is without a dedicate advocate above unit commander whose role is to advise on the generation and employment of military engineers.

The first principle – centralised control with decentralised execution – is the most important because through its application, the remaining principles are affected, and optimal employment of engineers is achieved. Instituting technical control of military engineers at the highest level is the recommendation that will remedy any misapplication or non-application of the principles. Having a dedicated senior officer with staff who are qualified and experienced across the range of military engineer trades, qualifications and specialisations will ensure the Australian Army’s limited but much in-demand engineer capabilities are generated, sustained and optimally employed to meet the commander’s intent at all levels. As British doctrine states, there should be only a single point of engineer advice.[37]

Montgomery’s quote about ‘never enough Sappers’ was based on his experiences as an army group commander in the Second World War. His sentiment is reflected in Australian doctrine as well as the doctrine of the British Army, U.S. Army and USMC. These doctrines have similar principle and planning factors, all of which are applicable above the brigade-level. The common principle, and most important for the employment of military engineers, is centralised control with decentralised execution; there should be a sole source of engineer advice at the highest practicable level. The Australian Army could do far worse that looking to how its allies adhere to this principle.

The Sappers really need no tribute from me; their reward lies in the glory of their achievement. The more science intervenes in warfare, the more will be the need for engineers in field armies; in the late war there were never enough Sappers at any time. Their special tasks involved the upkeep and repair of communications; roads, bridges, railways, canals, mine sweeping. The Sappers rose to great heights in World War II and their contribution to victory was beyond all calculations.
– Field Marshal Bernard Law Montgomery, 1st Viscount Montgomery of Alamein, 1945[38]