Reconsidering Rear Area Security

The 101st Airborne experience during Operation Market Garden


The 101st Airborne Division’s experience during Operation Market Garden is not generally as well understood as the exploits of the 82nd and 1st (UK) Airborne Divisions. However, the experience of the 101st offers a compelling example of how the failure to effectively secure a line of communication through the operation’s rear area had catastrophic consequences for the operation as a whole. Market Garden was an example of an enemy’s rear area rapidly becoming a friendly front line, and that same front line quickly transitioning to friendly rear area. While traditional interpretations regard the inability to secure bridges as the operation’s critical failing, the 101st experience shows the inability to secure bridges was actually the result of the failure to secure the vital supply line through the rear area.[1] The Hell’s Highway supply line was fundamental to the operation’s success because it enabled the projection of both reinforcing combat power and ongoing sustainment. However, it was constantly threatened by an enemy whose freedom of action allowed persistent disruptive attacks from the flanks. The focus of the operation was forward, but it was ultimately defeated by the Allies’ inability to secure the rear area. A force must be able to continuously secure its critical line of communication to enable all further actions; this security will almost certainly involve close combat; and, therefore, successful rear area security requires the assignment of an appropriate combat force to conduct it, or mission failure will be the result.

Contemporary Relevance?

The 101st Airborne experience in Operation Market Garden provides a lens through which to reconsider how rear area security has come to be viewed by modern militaries in order that we might understand where our conceptual gaps exist. For example, Australian Army doctrine states:

The purpose of Rear Area Security (RAS) is to prevent the enemy from disrupting command and control, combat support and combat service support in support of combat forces. In the non-linear, non-contiguous battlespace, RAS effectively concerns all force elements not postured for offensive or defensive action.[2]

This definition is not dissimilar, at least in philosophical approach, to those currently employed in U.S. Army and NATO doctrine. However, what is lacking in these definitions is the historical understanding that non-linearity and non-contiguity is nothing new. Indeed, what our doctrine (often ambiguously) considers to be non-linear and non-contiguous would be entirely familiar to most of the great captains of history—particularly as it relates to the criticality of securing lines of communication. Despite this, current definitions fail to address the need for and provide a concept to achieve a continuous connection between the fighting echelon and the logistics and command and control nodes to enable them in the non-linear, non-contiguous battlespace described.[3]

Figure 1: US Army Conceptual framework (2001) for non-linear, non-contiguous operations[4]

Existing definitions also suggest rear area security is static and somewhat separate from the combat operations occurring in the forward areas. Rather than making explicit that rear area security is a fundamental part of an operation’s design, and will most likely be a combat operation in and of itself, these definitions feed unhelpful characterizations about the separateness of rear echelon activities. This is a historically unsound bias that contemporary forces can ill-afford against adversaries who will exploit any lack of contiguity between combat forces and supporting enablers.

Market Garden was an example of an enemy’s rear area rapidly becoming a friendly front line, and that same front line quickly transitioning to friendly rear area.

The problem with current definitions may also be one of semantics. Rear area security suggests retaining control over an area cleared of a threat. In a non-linear, non-contiguous battlespace, however, the focus must be very much on rear area combat, because it can never be assured that the threat has been removed. A combat-focused approach also implies a more active posture and requires continued vigilance to defeat an ever-present threat. This means those forces inside a perceived rear area will always be an active part of the offensive or defensive actions undertaken by the force as a whole. Indeed, if easily recognisable front lines are not expected in the next war, then a force must be continuously postured to defeat attacks on its flanks and in rear areas with the same regularity and vigour as those once expected at the erstwhile front line.

This presents a vulnerability for Western militaries whose most recent experience with rear area security operations is shaped by the practice of working in and projecting from forward operating bases where threat forces able to physically deny lines of communication have been absent. That resupply and sustainment has been achieved mainly through contracted solutions and personnel movement conducted largely by air (with the luxury of total air superiority) only magnifies the potential for drawing the wrong lessons. It is therefore important for contemporary planners to reassess the importance of, and mechanisms to assure, security along extended and contested supply lines, as this is not something that has been critically tested by a peer adversary in recent memory. As a result, in the 21st century we should review the experiences of previous centuries (remembering that non-linear, non-contiguous challenges are nothing new) to better frame the challenges posed by sustaining a force where flank and rear threats may pose a greater risk to mission accomplishment than those at the perceived front line.

Operation Market Garden

 In the end, the battle for the corridor would decide the fate of Arnhem.[5]

On 17 September 1944, after the Normandy break-out, Operations Market (airborne assault) and Garden (ground follow-up) formed the Allies’ audacious attempt to outflank the German Siegfried Line. They provided an opportunity to cross the Rhine and potentially end the Second World War before the close of the year. The air and ground operations were wholly reliant on the success of each other to project the Allies across the Rhine. Market Garden demonstrated the trade-off between risk and security, particularly as it related to rear area security, extended lines of communication and the ability to resource and sustain fighting at a new front line.

Nowhere was the issue of rear-area security and its importance to enabling combat tempo more clearly demonstrated than in the 101st Airborne Division’s area of operations centred around Eindhoven. In this sector, the route connecting Eindhoven and Nijmegen became known as Hell’s Highway due to the intensity of the fighting. What makes this such an interesting study in rear-area security is the criticality to the Allied plan of keeping Hell’s Highway (through the city of Eindhoven) open and the challenges the 101st faced in their attempts to do so.

Figure 2: Sketch map of the Operation Market Garden plan, 17 September 1944[6]

As a result of the Allied airborne penetration into German-held territory and the availability of only a single line of communication for ground follow-up, the 101st Airborne sector rapidly became the Allied rear area for the remainder of the operation. The Allies, however, initially underestimated not only the German presence, but also their resolve in this area. This created the opportunity for German forces to impose delay on Allied forces traversing Hell’s Highway, allowing them to respond more forcefully around Arnhem. Tight operational timelines left limited tolerance for disruption of the logistics chain, therefore the imposition of delay starved the Allies of the reinforcements and sustainment they needed to enable follow-on actions. 21st Army Group would subsequently acknowledge the “course of the battle…entirely depend[ed] on the flow of vehicles along this axis.”[7] So, the critical vulnerability for the operation was not the final bridge, but rather adequate and timely resourcing to enable taking it—resourcing that relied on the security of the critical logistics node at Eindhoven and continued Allied freedom of movement along Hell’s Highway.

Materiel and reinforcements could not affect the seizure of a Rhine crossing without passing through Eindhoven and along Hell’s Highway as there was no means to bypass. The 101st Airborne was therefore tasked “to facilitate the advance of [XXX] Corps” and its 20,000 vehicles under General Horrocks—the majority of which carried supplies vital to the continuation of operations for the 82nd (Nijmegen) and 1st (UK) Airborne (Arnhem) Divisions.[8,9] As the operation’s rear area, the 101st sector received proportionately higher resupply on the assumption that this could move forward to Nijmegen and Arnhem with the XXX Corps column.[10] This assumption was, however, prefaced on the ability to keep the route open to enable link-up with forward troops.[11] As such, when the 101stwas unable to maintain route security it resulted “in complete hold up of all movement.”[12] This cutting of the highway:

[M]eant clogging the road for its entire length....For the men at Nijmegen and Arnhem, cutting the road was like severing an artery. The stuff of life – food, ammunition, medical supplies, no longer came forth.[13]

The Allied decision to advance along a single axis, reliant upon control of multiple crossing points, allowed the Germans to employ feverish flanking counter-attacks (characteristic of their tactics on the Eastern Front) to contest Allied control along the entire route. General Ridgway later acknowledged that Allied assumptions about the Germans, based on their hasty and “somewhat disorganised” withdrawal in the weeks prior, were proven incorrect during Operation Market Garden: “His command has been restored and invigorated, his control re-established, and he fights with the aid of strong ground defenses, closer to his sources of supply.”[13] Field Marshal Model had given General Student and his First Parachute Army “the dual mission of containing the British ground offensive opposite the Meuse-Escaut bridgehead [Belgian/Dutch border] and of destroying the 101st Airborne Division in the vicinity of Eindhoven.”[15] Student’s plan sought to disrupt the Allied supply line rather than retake ground. The Germans utilised the elevated and heavily wooded terrain astride Hell’s Highway to site their defences and used ad hoc battle-grouping to provide maximum combined arms effect. They also employed airstrikes where possible to assist in the interdiction of exposed logistics convoys. The Fallschirmjager in particular would attempt to draw the weary 101st paratroopers up and back along the route in order to exploit their fellow paratroopers’ lack of mobility and the requirement for them to hold the vital river crossings.[16] German actions would incur heavy casualties, but for every hour they denied the highway to the Allies it starved them of the vital resources needed on the Rhine. The cumulative contribution of each of these engagements resulted in the Germans achieving the delay they required to reinforce at Arnhem, which effectively culminated the Allied advance.

Figure 3: Map showing the sustained combat 101st Airborne undertook along Hell’s Highway during Operation Market Garden[17]

The German approach would lead the Commander of 101st Airborne, General Maxwell Taylor, to compare their actions to that of the American Indians raiding along railway lines through vulnerable settlements.[18] This analogy highlights the difficulty the 101st had in responding to German probes absent a defined defensive line and the ability to mass any reserves to respond. This allowed the Germans to constantly disrupt the Allied rear area around Eindhoven, forcing the diversion of valuable XXX Corps troops back along the route to keep Hell’s Highway open when they were desperately needed further north. The actions of 23 September 1944 provide an example of the overall effectiveness of the German tactics. Here, the Allied 43rd Wessex made a breakout from The Island north of Eindhoven and were advancing on Arnhem. There was no way for the Allies to exploit this opportunity, however, as the supplies needed to carry the momentum to Arnhem had been held-up by the Germans successfully cutting the highway in the 101st sector, around Koevering, for 35 hours. This “prevented an early crossing of the Rhine by the division,” and forced Horrocks to send forces back to reopen the route.[19]

The experience of the 101st Airborne around Eindhoven not only provides a different lens through which to examine the Market Garden story, it also highlights the importance of placing rear area security at the forefront of planning considerations.

The 101st experience securing the Operation’s rear area and critical line of communication was characterised by too much terrain to cover, insufficient combat power relative to the threat, and a lack of mobility. The result was numerous gaps for the Germans to exploit. The 101st mission called for the seizure of four highway bridges, the city of Eindhoven, and most importantly the maintenance of Allied momentum along Hell’s Highway. Like the Allies, the Germans were also constrained by crossing points; they were, however, unconstrained by having to conduct static defence, ensuring they could continuously outflank the Allied defenders. In his memoirs, Horrocks admits that to expect an airborne division to keep fifteen miles of road open was an enormous undertaking – particularly against the threat they faced – and he was not surprised that despite the division’s best efforts the Germans were able to cut the road three times.[20] This stemmed from the assignment (to a largely dismounted force) of a defensive frontage in excess of that typically given to a regular infantry division with integral mobility. Therefore, the 101st was “weak at every critical point and made necessary the most energetic shifting of troops to meet the numerous threats as they developed along this long corridor.”[21] This experience exposes the difficulties that even an elite combat unit can have in achieving comprehensive rear area security that enables an effective link between support, command and control, and combat forces.

Conclusion

The experience of the 101st Airborne around Eindhoven not only provides a different lens through which to examine the Market Garden story, it also highlights the importance of placing rear area security at the forefront of planning considerations; particularly as we must expect our adversaries will aim to sever vulnerable lines of supply. In 1944, German troops achieved this, and were able to critically undermine the Allies’ ability to generate the combat power required to ensure the operation’s success due to sustained interdiction in the rear area. Overall, the 101st Airborne’s fight along Hell’s Highway saw the Allies facing a threat to their rear area they had both underestimated and failed to resource an appropriate combat force to defeat. Unfortunately, these are errors that could all too easily be repeated—particularly if the experiences of Iraq and Afghanistan continue to feed unrealistic expectations about the prolonged viability and security of extended lines of supply.

We must devote greater effort to understanding what will be required to achieve rear area security against a peer adversary.

As such, the 101st Airborne experience raises a number of issues worthy of further consideration by contemporary planners at all levels of command. First and foremost is the requirement to critically assess (based on expected threat) the size, composition and competence of the force(s) tasked to achieve rear area security and maintenance of the connection between the fighting echelon and its support base. Linked to this is the requirement to conduct an operational risk assessment of the impact to the mission should the force assigned be unable to defeat a highly mobile adversary determined to exploit the non-linear, non-contiguous battlespace in which we expect to operate. Careful consideration of a force’s rotation and rest is also required, because those conducting rear area security are likely to be continuously in contact with the enemy, ensuring that rear area duties will offer little respite from combat. To account for these issues our doctrine would benefit from a reassessment of why we conduct rear area security, what we take the requirement to mean, and how it is envisaged that a force will achieve cohesive security from a rear area along vulnerable lines of communication. To better inform analysis during planning, doctrine should be supported through greater use of historical examples to illustrate the different rear area security challenges imposed by terrain, threat, size of rear area, availability of lines of communication etc.

Overall, planners must consciously consider rear area security as an active combat operation in a continuously contested environment, thus avoiding static conceptions of this vital work. This means that collectively we must devote greater effort to understanding what will be required to achieve rear area security against a peer adversary. It is therefore important to progress from envisaging rear area security solely as the protection of command and control and logistics nodes rear of the forward troops. Instead it must be viewed as a comprehensive, wide-area approach to combat operations against a similarly mobile adversary that envisages cohesive security from front to rear across a broad and probably porous frontage. Only through understanding the gaps implied by the non-linear, non-contiguous battlespace can we hope to mitigate the vulnerabilities inherent in sustaining future operations and ensure that combat power is available where we would seek to employ it, rather than where the adversary seeks to lure it.


Mark Gilchrist is a serving Australian Army officer and is a Featured Contributor at The Strategy Bridge. The views provided here are his own, and do not reflect any official position.


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Header Image: Anticipating contact with German forces at any moment, paratroopers of the 101st Airborne Division gather along a treeline in the Dutch countryside on September 18, 1944. (Warfare History Network/National Archives


Notes:

[1] Popular conceptions of Operation Market Garden are based around the notion that the plan was A Bridge Too Far with the operation failing due to an inability to capture the last bridge at Arnhem. This version, however, puts too much emphasis on actions at the bridges in Arnhem and Nijmegen and not enough on the role of the 101st Airborne Division along Hell’s Highway around Eindhoven one whose efforts the Garden (ground) component of the Operation arguably rested.

[2] Australian Army, LWD 3-0-3: Formation Tactics, 2016, 150.

[3] Taken here to mean a battlespace that has no clear boundaries or front line that would normally be expected to prevent an adversary’s ability to threaten or deny the lines of supply/communication that connect discrete military activities inside a friendly area of operation.

[4] FM 3-0, Headquarters Department of the Army, Washington, DC, 14 June 2001, http://www.globalsecurity.org/military/library/policy/army/fm/3-0/ch6.htm, accessed 31 May 17. I acknowledge that this framework is no longer in current US Army doctrine, but it is still a useful mechanism to visualise the concept.

[5] Cornelius Ryan, A Bridge Too Far (London: Coronet Books, 1974) 477

[6] http://www.warfaremagazine.co.uk/assets/images/articles/medium/20130917104811.jpg, accessed 25 May 17

[7] 21st Army Group, Operation ‘Market Garden’, 17-26 Nov 1944, 6

[8] 82nd Airborne and 101st Airborne admin and load orders

[9] 21st Army Group, Operation ‘Market Garden’, 4

[10] Anonymous, 38 Group Operation Order, No. 526: Operation ‘MARKET’ (date unknown) 4

[11] Tim Saunders, Hell's Highway: US 101st Airborne and Guards Armoured Division (Barnsley: Pen and Sword Military, 2011) 74

[12] XXX Corps war diary, as cited in Saunders, Hell’s Highway, 163

[13] 101st Airborne Division official history as cited in Steven E. Ambrose, Band of Brothers:E Company, 506th Regiment, 101st Airborne from Normandy to Hitler's Eagle's Nest (New York: Touchstone, 1993) 131-32

[14] XVIII Corps, Report on Airborne Phase of Operation Market Garden (4 Dec 1944) 5

[15] Charles MacDonald, The Siegfried Line Campaign (Washington: Centre of Military History, 1963) 142

[16] Volker Griesser, The Lions of Carentan: Fallschirmjager Regiment 6, 1943-45 (Havertown: Casemate Books, 2014) 172

[17] http://www.flamesofwar.com/Portals/0/all_images/Historical/MarketGarden/Market-Garden-History-07.jpg, accessed 25 May 17

[18] Ryan, A Bridge Too Far, 372

[19] 43rd Wessex G-4 as cited in Saunders, Hell’s Highway, 161

[20] Brian Horrocks, with Eversley Belfield and H. Assame, Sir Brian Horrocks: Corps Commander (London: Sidgwick and Jackson, 1977) 106

[21] 101st Airborne Division, Report of Airborne Phase (17-27 Sep 44), Operation Market (date unknown) 1