CASE STUDY CONCEPT: Military Logistics 101 — “An Army Marches on Its Stomach.”
In the spirit of the saying, “amateurs talk strategy and professionals talk logistics”, lets look at the campaigns of Alexander the Great. For those who think that his greatness was only due to his ability to dream up bold moves and cut a dashing figure in the saddle – think again.
Alexander was a master of supply chain management and he could not have succeeded otherwise. The authors from Greek and Roman times who recorded his deeds had little to say about something so apparently unglamorous as how he secured supplies for his army. Yet, from these same sources, many little details can be pieced together that show the overall supply chain picture and how Alexander managed it.
Modeling Alexander’s Supply Chain
A modern historian, Donald Engels, has investigated this topic in his book Alexander the Great and the Logistics of the Macedonian Army (Engles, Donald W., 1980, Alexander the Great and the Logistics of the Macedonian Army, Los Angeles, CA: University of California Press).
Using SCM Globe and information from Donald Engel’s book we have created a model of Alexander’s supply chain that supported his campaign in Afghanistan. As this campaign begins, Alexander has defeated the Persian King Darius and is organizing a supply chain to draw on the farms and workshops of Persia to support his advance into Afghanistan. This case study will give you insight into what Napoleon meant when he said, “An army marches on its stomach.” An army can only go where there are supplies to support it (or it will perish). The screenshot below shows Alexander’s supply chain as he advanced into Afghanistan toward Kabul.
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The orange arrows show his planned route of march and Kabul is circled in yellow. On the left side of the screen as the supply chain crosses from Persia into Afghanistan is the city of Herat, which was first founded by Alexander around 330 BC as the main supply depot for his Afghan campaign.
Alexander Used Logistics as a Competitive Advantage
It was because Alexander’s army managed its supply chain so well that it was able to achieve its brilliant successes. Alexander’s army had a logistics structure that was fundamentally different from other armies of the time. In other armies the number of support people and camp followers was often as large as the number of actual fighting soldiers. This was because armies traveled with huge numbers of carts and pack animals to carry their equipment and provisions. And those carts and pack animals needed lots of people to tend them. In the Macedonian army the use of carts was severly restricted. Soldiers were trained to carry their own equipment and provisions. Other contemporary armies did not require their soldiers to carry such heavy burdens but they paid for this because the resulting baggage trains reduced their speed and mobility.
The result of the Macedonian army’s logistics structure was that it became the fastest, lightest, and most mobile army of its time. It was capable of making lightning strikes against an opponent often before they were even aware of what was happening. Because the army was able to move quickly and suddenly, Alexander could use this capability to devise strategies and employ tactics that allowed him to surprise and overwhelm enemies that were numerically much larger.
The picture that emerges of how Alexander managed his supply chain is an interesting one. For instance, time and again the historical sources mention that before he entered a new territory, he would receive the surrender of its ruler and arrange in advance with local officials for the supplies his army would need. If a region did not surrender to him in advance, Alexander would not commit his entire army to a campaign in that land. He would not risk putting his army in a situation where it could be crippled or destroyed by a lack of provisions. Instead, he would gather intelligence about the routes, the resources, and the climate of the region and then set off with a small, light force to surprise his opponent. The main army would remain behind at a well-stocked base until Alexander secured adequate supplies for it to follow.
Imagine you are in charge of Alexander’s supply chain. He has sketched out what he wants to do and now he’s looking to you to create and operate the supply chain that will support his Afghan campaign. His first objective is to capture Kabul. How will you deliver the supplies his troops need to achieve that objective?
Let’s make the following estimates and assumptions to define some operating parameters for this case study:
- For products we’ll use a generic unit of inventory which is a mix of required products in a 1 cubic meter package. We’ll call this inventory “All Purpose Material” (APM)
- 1 unit of APM has a cube volume of 1 cubic meter and cube weight of 40 kilograms
- 1 unit of APM can sustain 5 soldiers for a day; each soldier requires 0.2 units of APM per day; that’s 8 kilos of supplies per soldier per day
- So it takes 2,000 units of APM per day to support 10,000 troops; 500 units of APM will support 2,500 troops per day
- Assume Alexander needs to support 20,000 soldiers on this campaign. Some of these soldiers will be at the head of the advance to do the fighting and some will be spread out along the length of the advance to operate and protect the supply line.
- Alexander’s supply chain vehicles are wagons drawn by horses, oxen or mules; a wagon has a carry volume of 5 cubic meters and a carry weight of 200 kilograms
- A wagon has a speed of 3 kilometers per hour
- A wagon can carry 5 units of APM and support 25 troops per day
- 100 wagons can support 2,500 troops per day
- Vehicles can be units of 50 or 100 or 200 ox carts
- The route taken by Alexander in his march on Kabul is identified in this case study – the topography makes it the only practical route through which to move 20,000 troops using the means available to Alexander at that time.
FIRST CHALLENGE —Alexander’s plan is to march to and capture the Afghan fortress at Kabul, and then move on further into Afghanistan from there. Can you create a supply chain to support this campaign? That’s a pretty theoretical question until you start playing with the design of different supply chains and learning from simulations about what works and what doesn’t.
Objective: Design a supply chain that supports 10,000 – 12,000 troops at a staging area outside of Kabul. Get the supply chain to run for 15 days.
At the start of this campaign there are factories set up in three locations in Persia to produce food, weapons and other needed material. Inside Afghanistan there are supply depots established in Herat and Shindand. And there are military bases at Delram and Kandahar. The screenshot below shows operating results from one simulation.
This simulation shows operating results from the Alexander the Great supply chain model in the SCM Globe library. We can see the depot at Herat runs out of storage space for supplies (red circle indicates point of failure), and at the same time supplies on hand at Kandahar (circled in blue) are being consumed faster than they are delivered. Two upward spikes in the otherwise downward sloping blue line on the graph show arrivals of wagons carrying supplies. But arriving supplies do not keep up with daily demand. More wagons are needed to move up more supplies, and other closer sources of supply need to be found (blue arrows).
As you extend the supply chain toward Kabul, you need to set up new facilities and deliver supplies to support the troops. Each new facility requires storage space and soldiers to protect it. As you create this supply chain and run simulations you will get an intuitive feel for what it is like to run a supply chain under the conditions Alexander and his soldiers operated in (and although the wagons are faster, things are not that different even today).
Here are some things to think about as you work with this first challenge:
- Existing facilities can be expanded to become depots by increasing their storage capacity so supplies can be stockpiled in them to support deliveries of supplies to facilities further along the supply chain
- Establish a forward base to hold the 10,000 – 12,000 troops who will attack Kabul. This base should be a day’s march outside of Kabul (40 – 45 km); just inside of the yellow circle around Kabul shown in the screenshots above
- How will you move up enough supplies to support those troops in the forward base for 15 days? Or 30 days?
- Define the number of vehicles at each facility and their routes and product delivery quantities.
- You may want to establish new facilities for storing supplies in between Kandahar and Kabul
- Remember to adjust demand for APM at each facility to supply the troops stationed at those facilities to protect them
- Assume the closer you get to Kabul the more troops need to be stationed at a facility to protect it and to escort the supply convoys
- Experiment with the number of wagons needed to support different allocations of troops in different facilities. How many wagons do you need?
- Are you starting to understand how difficult it is to supply large numbers of troops as they advance across enemy territory?
- What will Alexander say when you tell him how many wagons you need?
SAVE BACKUP COPIES of your supply chain model from time to time as you make changes. Click “Save” button next to your model in Account Management screen. There is no “undo”, but if a change doesn’t work out, you can restore from a saved copy. And sometimes supply chain model files (json files) become damaged and they no longer work, so you want backup copies of your supply chain to restore from when that happens.
SECOND CHALLENGE — Alexander thinks you are asking for way too many wagons. Find ways to streamline and redesign your supply chain to do more with less.
Objective: Reduce use of wagons as much as possible while still delivering supplies needed to support 10,000 – 12,000 troops at staging area outside Kabul for 15 days.
Hint: Alexander and other armies of that time lived off the land; they requisitioned local supplies from towns they passed through. From your work on the first challenge you can see why. It takes a huge number of wagons to transport all the supplies needed by an army. So it is best to requisition supplies of food, wood, leather and other commodities from local sources. Use wagons only to carry the hard to find or make items such as heavy weapons, armor, tents and cooking utensils.
Alexander timed his campaign to begin early in the spring as the first grain harvests were made and the grain became available at storehouses in the cities he passed through. Assume most of the APM needed by the army (about 85 percent) is food, water and other material (cloth, leather, wood, metal) that could be acquired locally. Alexander’s army carried some of their supplies, such as armor, weapons and tents, and they requisitioned or purchased the rest of what they needed from villages and cities along the way.
To the southwest of Delram in Alexander’s day (circa 330 B.C.) there was a highly productive agricultural area known as Zarangea (a smaller area is now called Zaranji). Notice the green strips of cultivated land that follow the rivers through this otherwise desert landscape; that is where much of the food and other supplies were (and still are) produced. Southwest of Kandahar is a facility called Garmsir and it too is a productive agricultural region because of irrigation provided by the rivers that flow into the desert.
Assume you can meet 85 percent of demand for APM from locally produced sources. This significantly reduces the demand for wagons to move APM over long distances. And if the soldiers carried some of the APM themselves it further reduces the demand for wagons. Assume each soldier can carry weight up to 30 kg and volume up to 0.2 cubic meters.
Notice there are two facilities situated in fertile agricultural areas to the south of the current supply chain. Both of these places are located in or near fertile desert farming areas made possible by irrigation works built by the local inhabitants. Switch to the satellite view (button in upper left corner of screen) and zoom in on these facilities. See the green, agricultural land following along the course of the rivers as they flow through the desert landscape.
Acquiring Supplies Locally Reduces the Need for Wagons
In the supply chain model the facilities each have daily production rates for APM to represent the amount of food and raw materials they produce. Assume the Zarangea facility has 200 wagons available for delivering APM to another facility such as Delram. Assume there are 150 wagons available at Garmsir (yellow circle) and they can be used to supply APM to Kandahar (blue circle). Also assume Kandahar produces 900 units of APM per day itself because you can see it is situated in the middle of a green agricultural region like Garmsir.
If you put new facilities in locations between Kandahar and Kabul that are also located in agricultural areas that support production of food and raw materials, then you will need fewer wagons to haul the remaining supplies needed by the army. Switch to satellite view and zoom on the route the army will take to Kabul. Look for areas that show concentrations of agricultural activity. Those make good locations for new depots and forward bases needed to support Alexander’s advance on Kabul.
Assign daily production rates for APM to these facilities based on much green land you see around these facilities; the more green land the higher the production rate. Use Garmsir and Kandahar as points of reference for your estimates – see how much bigger or smaller are these areas of green land compared to Garmsir or Kandahar.
If 85 percent of needed APM can be acquired locally, how many wagons are required to make this supply chain work? How much APM needs to be produced at facilities between Kandahar and Kabul and how much needs to be delivered from other facilities to support the troops? Where would you put the new facilities and why? How many troops would you station at each facility to protect it and why?
For ideas on how to expand this supply chain see “Tips for Building Supply Chain Models” for useful techniques. There are also useful ideas to be found in the section “Reducing Inventory and Operating Costs”
THIRD CHALLENGE – Alexander’s plans call for the army to continue its advance after taking Kabul. The army will live off the land on this march. Troops and carts will carry the equipment they need (armor, tents, weapons, utensils) and they will buy or requisition the rest from the cities and towns they pass through (85% of daily the APM requirements). Alexander wants your ideas on how to keep the army supplied on the march.
Objective: The army will move north toward the cities of Bukhara and Samarkand. Create a supply chain design that merges battle strategy and logistics to give Alexander the military advantage he needs for success in his Afghan Campaign. Define routes to support the army as it advances on these two cities.
Assume 6,000 troops are needed to capture Sarmarkand and 5,000 are needed to capture Bukhara. Find routes for 6,000 troops to reach Samarkand and for 5,000 troops to reach Bukhara. You can explore sending troops on just two routes to the two cities, or you may find multiple routes for different sized units to follow. These multiple routes must enable the units that follow them to converge in appropriate numbers on the two cities. All units need to arrive at their designated cities within a day or two of each other.
We are modeling a special sort of supply chain here. It is composed of a series of one-time, one-way transactions that occur as Alexander’s army travels across the landscape toward its objectives. The only thing that matters is creating a plan of advance where all units are able to pick up the supplies they need as they travel, enabling them to reach their assigned cities in a timely manner.
Modeling and Simulating the Plan of Advance
Because the army is living off the land and not staying in any location as it moves toward the two cities, a good way to model this supply chain is to think of different sized units in Alexander’s army (500 men, 1000 men, 2000 men etc.) as being vehicles. These vehicles can use different routes to get to their final destinations of Bukhara and Samarkand. The starting location for all vehicles is Kabul. Find routes that support different sized vehicles as they move from facility to facility on multi-stop routes that advance them toward their assigned cities.
Routes connect facilities located at points where agriculture and food production can occur as shown in the satellite pictures. Each facility has a daily production rate and an initial on-hand amount of APM related to the size of the farmland surrounding the facility. Estimate initial on-hand amounts of APM based on the amount of green farmland surrounding these facilities. Make educated guesses about the size of the spring harvest for each facility and deduct some APM to account for local demand, the remainder is the initial on-hand amount. The more surrounding farmland, the higher is the initial on-hand amount of APM, and the higher the daily production rate.
Create a plan where the simulation shows all units can reach the city they are assigned to attack in a timely manner. And where the simulation also shows all units can make this trip while picking up the supplies they need at each stop on their routes. Show the planned route of advance for each unit as a multi-stop delivery route. A vehicle representing a unit will have the city it is assigned to attack as the last stop on its multi-stop route.
Assume units of Alexander’s army can carry up to four days of supplies with them. Represent smaller units (up to 1000 soldiers) as a medium size truck with a speed of 5 km/hr., and for larger units use a large truck with a speed of 2 km/hr. Plot routes for these vehicles to follow. Given the speeds at which units can move and the distances involved, it will take some number of days for the units to travel from one facility to the next.
You can see travel times and distances in the Edit screen when you select a route and open its dialog box. Use those travel times to calculate pick-up quantities at each stop on a unit’s route of advance. If it only takes half a day to reach a given facility, then the vehicle picks up half its daily needs. If it takes 3 days, it picks up three times its daily needs. And remember, no unit can go for more than four days without resupply from a facility it passes through.
Plan of Advance is Guided by Logistics Considerations
As a general rule, you want to pick routes that follow rivers and go from one green agricultural area to the next as units move toward their assigned cities. The facilities on the routes you choose must be productive enough to generate adequate on-hand inventory to fill the pick up amounts of the units (vehicles) that pass through. See Tips for Building Supply Chain Models and scroll down to the Routes section to see tips for creating vehicle routes where there are no existing roads on the map.
Consider dividing the army into smaller groups. This way each group has a smaller logistics footprint so there are more choices in selecting possible routes of advance. This gives Alexander more options for strategy in the campaign. It plays to a major strength of his army which was the ability to surprise and overwhelm larger opponents by moving quickly over the landscape because of its lighter and more agile supply chain (fewer wagons, less equipment, soldiers trained to carry more).
In the simulations when units do reach their assigned cities they will then return to their starting location in Kabul, but that return trip can be ignored. Make the delay between departures for each unit a large number so it does not begin its route again during the simulation run. And set vehicle carry weights and volumes to a very large number to accommodate the amounts of APM they will pick up. In this model APM production rates at facilities and vehicle speeds and pick-up quantities are the determining factors, not vehicle carry weights and volumes (the APM picked up would be consumed day by day anyway). Also set storage capacity at Kabul to a very large number to handle the amount of APM on the returning unit vehicles.
Some questions to think about as you work in this third challenge:
- Assuming the amount of APM on-hand at Kabul was captured intact, how long could Alexander’s troops occupy Kabul before needing to be resupplied? Given the rate of APM production by Kabul itself, how many troops can it support without additional supplies from elsewhere?
- If the whole army stayed in Kabul for four days, and then moved on leaving 500 troops behind to guard the city, how many days would the remaining supplies of APM support the troops who stayed in Kabul?
- How much of the APM supplies in Kabul could the departing troops take with them to consume on their march?
- What are the best places in between Kabul and those two cities where the army could find food and other supplies?
- Would it be best to keep the army together in one group and advance first on one city and then the next – or is it best to divide the army into smaller groups that each advance independently on their assigned city? Why?
- If you decide to divide the army into smaller units, how do you reconcile that with the warning, “don’t divide your force in the face of a superior foe?”
- What routes of advance will you recommend to Alexander? What advantages do these routes offer – logistical and strategic?
- What will you tell Alexander when he asks you how many troops can be supported on this march beyond Kabul?
As you work with this model and identify the possible routes Alexander’s army can take you will see how strategy and logistics are tightly linked. You will appreciate how logistics considerations affected strategy in Alexander’s time — and how it still does today.
MISSION REPORTING TEMPLATE — There is reporting template with an operations report and a performance dashboard for analyzing your simulation data. The template is built for a 15-day period. You can import your simulation data after trimming it for 15 days (scroll down to bottom of Analyzing Simulation Data). The operations report shows facility and product detail, and the dashboard shows where the best opportunities are for improvement. You can download a copy of the mission reporting template here.
The reporting template is set up for the Nepal Earthquake DR supply chain, but look at how the reports read the product and simulation data – you will see how to change the spreadsheet as needed to accommodate this case study.
This reporting template will be helpful for analyzing simulation results from the first two challenges. But it will not be very relevant for analyzing simulation results from the third challenge. In the third challenge the only thing that really matters is to find routes that enable all units (vehicles) to reach the last stop on their multi-stop routes — the cities they are assigned to attack.
To share your changes and improvements to this model (json file) with other SCM Globe users see “Download and Share Supply Chain Models”
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