Introduction

War, by its very nature is unpredictable. Actions taken at the tactical, operational, and strategic levels to address one problem may inadvertently create another entirely unexpected one. This is especially true when measures are adopted quickly to address an unexpected threat.  This is a common-sense proposition; the notion that certain actions may generate unintended consequences is hardly a ground-breaking idea. Nevertheless, occurrences of unintended consequences are worth examining in more detail because decision makers seek to maximise the utility of their actions and limit uncertainty. 

The US military’s experiences with wheeled vehicles in Iraq and Afghanistan is an apt case study from which to explore the law of unintended consequences in a military setting. This case study examines how the US military’s actions to increase the survivability of its wheeled vehicles did deliver greater protection against explosive and ballistic threats but subjected the occupants of the vehicles to a greater risk of accidental death.

The Vulnerabilities of the HMMWV in Iraq and Afghanistan

The US Army’s workhorse, the High-Mobility Multipurpose Wheeled Vehicle (HMMWV/Humvee) was not designed to sustain heavy small arms fire or explosive blasts. When the HMMWV was introduced in the 1980s, its primary role was to shuttle troops and supplies to where they were needed behind the front lines. It was also used as an ambulance and mobile missile launcher platform. Its main advantages were in speed and manoeuvrability.

The HMMWV initially performed well in the early phases of Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF). In Afghanistan, in particular, the HMMWV’s manoeuvrability was especially welcome in rough and mountainous terrain. Some personnel even detached the vehicle’s doors to further enhance manoeuvrability.

However, the nature of operations in Iraq and Afghanistan meant that the HMMWV was increasingly relied upon as a combat vehicle. This is when the HMMWV’s lack of amour, which could not withstand sustained small arms fire and blasts from improvised explosive devices (IEDs) became a problem.

To address this vulnerability, troops in-theatre began improvising their own armour solutions. For example, in March 2003, soldiers from the 223rd Military Intelligence Battalion hired locals in Iraq to place makeshift armour on the 12 unarmoured HMMWVs they were operating. A steel lining was added to the floorboards and cargo areas of the vehicles, as well as steel doors and enclosures for the gunners. Sandbags were added for additional protection. 

This so-called ‘hillbilly armour’ varied in effectiveness and often granted relatively limited protection. Sandbagging the floorboards of a HMMWV was often not enough to stop an IED blast tearing through the vehicle’s undercarriage and killing or maiming its occupants. In some cases, the additional improvised steel armour proved counterproductive because poor quality metal would turn into shrapnel if hit by an explosion.

^ A HMMWV with improvised 'hillbilly armour' in Iraq, c. 2004 (Source: tanko.grad.net)

Solving one problem creates another…

Between August 2003 and April 2005, the US military attempted to address the vulnerability of the HMMWV by introducing up-armoured variants. Attachable armour kits were shipped out to vehicles already in-theatre so that personnel could retrofit them with increased protection. Concurrently, the production of up-armoured HMMWV variants was intensified to ensure that the vehicles arriving in Iraq and Afghanistan had better protection.

The up-armouring program did succeed in decreasing the vulnerability of HMMWVs to weapons attacks and blasts from IEDs until many of the vehicles were replaced with more durable Mine-Resistant Ambush Protected (MRAP) vehicles between 2007 and 2012. However, the additional armour created a number of other unintended problems that troops now had to deal with.

The HMMWV was not originally designed to support the weight of much additional armour. Overall performance in the areas of speed and manoeuvrability was negatively impacted and wear and tear on the gearbox and other components necessitated more frequent maintenance, repairs, and replacements.

More worryingly, the cumbersome addition of armour made the HMMWVs more susceptible to accidents, particularly rollovers. As one study notes, the frequency of rollover accidents involving HMMWVs during OIF and OEF increased significantly between 2003 and 2005, during the up-armouring period. The peak of rollover accident occurrence coincided with the up-armouring program’s year of completion in 2005. That year, there were a total of 108 rollover accidents, in which 111 personnel were nonfatally injured and 33 fatally injured.

Another unintended consequence of up-armouring was that the heavier vehicle doors were more likely to jam shut during an accident or attack. As a result, personnel were sometimes trapped in their vehicles when they needed to quickly egress to return fire or seek medical attention after a rollover accident.

Solutions

Gradually, Research produced a better understanding of how rollover accidents were occurring. A 2007 computer modelling simulation of rollover accidents found that at certain speeds, changes in the HMMWV’s stabiliser bar influenced the likelihood of a rollover.  Variations in the vehicle’s mass and centre of gravity likewise had an effect. A 2009 study found that sharp turns on offroad conditions coupled with deeper outside-wheel sinkage and greater sand build-up increased the likelihood of a rollover.

A better understanding of why rollovers occurred facilitated measures to prevent them, or at least make such accidents survivable. Best practices and training to avoid rollovers became more of a focus. Rik Cox, an officer in the US Army's Forces Command (FORSCOM) Safety Division developed the Humvee Egress Assistance Trainer (HEAT), which has allowed soldiers to safely practice escaping a replica HMMWV capable of rotating 360°. In the two years following the introduction of the HEAT, rollover incidents and associated fatalities in combat both dropped by more than 60 percent.

Measures were also introduced to address the issue of heavily armoured doors jamming. For example, ‘rat claw’ and HMMWV crew Extraction D-ring allows troops to wrench open or tear off a HMMWV’s door with the assistance of another vehicle if it cannot be opened.

Unfortunately, the HMMWVs that remain in service are still susceptible to rollovers, albeit less so than before. On 28 May 2022, one soldier was killed and three wounded when their HMMWV rolled over and crashed at Fort Bragg, North Carolina. There are concerns that safety upgrades like electronic stability control and antilock brakes have not been fitted quickly enough to the aging HMMWV fleet. 

Conclusion

Overall, the decision to upgrade the HMMWV’s armour was correct. Even during the years in which rollover fatalities peaked, the number of personnel killed by IEDs dwarfed those who lost their lives in accidental crashes. Nevertheless, successful efforts to reduce the threat posed by the enemy resulted in a heightened risk of injury or accidental death.

Further discussion should take place to determine how foreseeable the unintended consequences of up-armouring were. Furthermore, the speed at which solutions to these problems were adopted and made available to operators of the HMMWV should be examined.

This case study demonstrates the complexity of decision-making in war. A seemingly straight forward measure to counter a threat – in this case the addition of armour to protect against small arms fire and IEDs – may lead to an array of negative unintended consequences. These unintended consequences do not necessarily indicate blunder at the tactical, operational, or strategic levels. Indeed, additional protection was an absolute necessity in this case study. However, it does demonstrate the need to constantly and quickly react to, and if possible, pre-empt, a myriad of adverse variables.