Logistics and Alexander the Great's Army
The reading of Xenophon's Anabasis highlighted the importance of logistics in the strategic and tactical considerations of military commanders in the days of the Persian and Greek empires. Any reading of Alexander the Great's pathway to conquest raises some very interesting questions of strategy. Why, after the battle of Issus in November, did Alexander the Great move towards Egypt rather than attack the heart of the Persian Empire? Why, after the battles in the Indus Valley, did Alexander the Great choose to move across the Gedronian Desert? In both cases, how did he provision the army and what risks did he take in following these pathways?
Thankfully, there is a book that tackles these challenges. Donald Engels has tackled the subject of the logistics of the Macedonian Army in his Ph.D. thesis. While there are many books that have analysed the battles of Alexander the Great (at crucial battles at Issus and Gaugamela against Darius III in particular), this is a groundbreaking book in understanding the military strategy of Alexander the Great on a broader front. Engels specifically looks at the impact of logistics and geography on military strategy (while of course not denying the importnace of political and military events).
Ask yourself the question, for how many days can an army survive by carrying its own food and water? In these days of processed high nutrition meals and a military logistics machine that can carry food across continents to supply an army, it may sound like a silly question. (For example, the U.S. Army in Iraq must have a significant portion of its food supplied from the US and Europe). However, in the days of Alexander the Great this was a seriously important and reasonable question to ask. Alexander the Great had to cross deserts with minimal food availability and even less water available a number of times (e.g. on the road to Egypt, when attacking Babylon, and when returning from the Indus Valley to Persepolis).
The answer depends on a small number of questions and of course the assumptions made in answering those questions:
• How much food and water do people (soldiers and followers) and pack animals (horses, mules, camels) need per day to survive?
• How much food and water can each of these carry in addition to the other items required (battle equipment, tents and housing, loot captured along the way)?
• What is the composition of the armed forces (horsemen, hoplites and archers)?
• How many and what type of followers do you allow to be the baggage of an army?
The answers to these questions allow one to estimate how long an army can survive by carrying its own food.
The answer calculated by Engels (1978 pp.22). is that "an army whose supplies are carried by animals and men cannot advance through desert where neither grain, fodder or water is available for more than four days. If the army were fed full rations, it could not advance for more than two days without incurring heavy casualties." This, if I have understood Engels correctly, for an army that did not have any women or children following, had the soldiers carrying their own armour and limited support followers to one for every three soldiers.
If you want to know the detailed assumptions he made, it's worth reading the book. Just for the record, here are the key assumptions made:
• Each soldier requires the nutritional equivalent of 3 lb of grain and 2 quarts of water per day (and I'll let you convert that to metric*),
• Each horse or mule would require forage of 10 lbs of chaff or straw plus 10 lb of grain per day and 8 gallons (32 quarts) of water per day,
• The average pack animal can carry 250 lb while the average soldier can carry up to 80 lbs of food and equipment,
• One pack animal was required for every 50 combatants to carry noncomestibles i.e. items such as tents and other camp necessities.
If you'd like to check how these were calculated and estimated, you will need to refer back to Engels (1978, pp. 11-25 plus Appendix 1:Rations).**
Having answered that question, one can then ask other questions based upon different availabilities of food and water along the way as well as the capacity of a logistics support system to bring the food to the soldiers. This is where the importance of naval supply vessels becomes critical. Alexander the Great controlled the sea sufficiently to bring food supplies in from other regions using ships. Knowing that Athens controlled the grain supply from the Black Sea to the Mediterranean and that Athens was an ally (no matter how reluctantly) of Alexander the Great means that the range of his army could be extended greatly. Ships are much more efficient than pack animals in carrying food supplies and water.
The battle at Issus was fought in November 333BC. Food supplies would have been limited at that stage if foraged from the land. The next crops would be in five to six months time, in the Spring of 332BC. Had Alexander moved inland, he would have had difficulty finding sufficient food for his army in hostile territory. He was far better off moving along the coast, capturing cities along the way and securing some food supplies that way while using the naval forces to provide grain from what can only be assumed was from the Black Sea. By moving towards Egypt, Alexander was also securing one of the few regions able to provide a surplus of food for the Persian Empire as well. He was cutting off a vital resource. (There were political reasons for doing so as well. Alexander would have known that the Persians had alienated the local population in Egypt by desecrating their temple of the sacred calf, providing him with an opportunity to overthrow the Persian governors and tax tributes).
Alexander left Egypt in the middle of 331BC (i.e. when he had secured food supplies from the recent harvest and was able to move into the heart of the Persian Empire having consolidated his position in Egypt). The battle at Gaugamela (modern day Irbil in Iraq) was held on October 1st 331BC. The distance between Alexandria in Egypt and is about 870 miles (or 1400 km). Engels (Appendix 5, pp.153) has calculated the fastest the army could have moved as 20 miles per day. So, at breakneck speed and allowing for no opposition it would have required 44 days with no rest to make that journey (never a realistic assumption). At least half, if not more, of that distance is traveling inland from the coast depending upon the route actually taken. It would have required a strong local knowledge of food and water supplies to ensure that the army of Alexander the Great would arrive in a fit condition to fight. That also assumes that Alexander knew where they would be fighting in advance of leaving Egypt.
Of course, a large army of 40,000 infantry and 7,000 cavalry (Wikipedia, 2007) is unlikely to move that fast anyway and it is likely at each step of the way inland, Alexander had to secure the territory to ensure his retreat was also protected (just in case). During the journey inland Alexander the Great had the viceroy of Syria (named as Arrimas) removed for failing to collect supplies needed for the inland journey (Engels, 1978 pp.66).
The interesting point is that while Alexander had lost the logistics advantage of being supplied by sea vessels once he left the Mediterranean coast, he still had the advantage of travelling much faster than the Persian army could for the reasons mentioned earlier in this blog i.e. no women and children and fewer support personnel. It was only after the battle of Gaugamela that Alexander allowed the army to have women and children following in the baggage train. That was when he had essentially captured one half of the Persian Empire (from Egypt through to modern Iraq) and all that remained was modern day Iran, Afghanistan and parts of modern Pakistan.
The next time that Alexander used ships to transport food was in the march from the Indus back to Persepolis through the deserts of Southern Iran. The plan was breathtakingly simple in concept and obviously difficult but not impossible in practice. Water would be supplied by the troops to the fleet and the fleet would provide food to the troops. However, the very monsoon supplying the water was the reason why the fleet was unable to sail until October, and the detailed preparation was in vain. (For more information, you must read Engels pp. 110 - 117). That Alexander the Great found a way though was a tribute to his ability to take risks and knowledge of logistics. Far from being irrational, he showed the greatest courage of his career in making those decisions.
At this stage I am not aware of any follow-up studies to the work of Engels but I'm happy to receive information on more recent studies that support or cast doubt on the findings.
Why are these findings about the importance of logistics and geography to the military strategy of Alexander the Great so important? They go to the very heart of Alexander's state of mind during these campaigns, especially the campaigns through the Gedrosian Desert and Southern Iran. It has been suggested that Alexander the Great was already "unstable" of mind at the time and that the campaigns were a a way of punishing the Macedonian soldiers who had effectively revolted in the Indus Valley campaigns against going further into India. Certainly he would have been very disappointed and angry, but his actions take on a very different light given the logistic and geographic situations he was facing and the possibility he had received disturbing news from Persia about the behaviour of his satrapal appointees.
That has to be the topic for another blog. I have some more research to do now :-) as this new insight demands investigation.
Notes:
* OK, 3 lb is equivalent to 1.4 kg approximately and 2 quarts (US) approximately equal 1.9 liters of water.
** You'll also want to know that a ship can carry 53,360 gallon of water plus the weight of the amphorae (Engels, 1978 pp. 58 n.26). That's 202,768 litres of water by volume or a weight of 202,786 kilograms.
Bibliography:
Cities located close to Alexandria, Egypt http://www.timeanddate.com/worldclock/distances.html?n=426 (read 07 April 2007)
Engels, Donald W. Alexander the Great and the Logistics of the Macedonian Army University of California Press, 1978
Thankfully, there is a book that tackles these challenges. Donald Engels has tackled the subject of the logistics of the Macedonian Army in his Ph.D. thesis. While there are many books that have analysed the battles of Alexander the Great (at crucial battles at Issus and Gaugamela against Darius III in particular), this is a groundbreaking book in understanding the military strategy of Alexander the Great on a broader front. Engels specifically looks at the impact of logistics and geography on military strategy (while of course not denying the importnace of political and military events).
Ask yourself the question, for how many days can an army survive by carrying its own food and water? In these days of processed high nutrition meals and a military logistics machine that can carry food across continents to supply an army, it may sound like a silly question. (For example, the U.S. Army in Iraq must have a significant portion of its food supplied from the US and Europe). However, in the days of Alexander the Great this was a seriously important and reasonable question to ask. Alexander the Great had to cross deserts with minimal food availability and even less water available a number of times (e.g. on the road to Egypt, when attacking Babylon, and when returning from the Indus Valley to Persepolis).
The answer depends on a small number of questions and of course the assumptions made in answering those questions:
• How much food and water do people (soldiers and followers) and pack animals (horses, mules, camels) need per day to survive?
• How much food and water can each of these carry in addition to the other items required (battle equipment, tents and housing, loot captured along the way)?
• What is the composition of the armed forces (horsemen, hoplites and archers)?
• How many and what type of followers do you allow to be the baggage of an army?
The answers to these questions allow one to estimate how long an army can survive by carrying its own food.
The answer calculated by Engels (1978 pp.22). is that "an army whose supplies are carried by animals and men cannot advance through desert where neither grain, fodder or water is available for more than four days. If the army were fed full rations, it could not advance for more than two days without incurring heavy casualties." This, if I have understood Engels correctly, for an army that did not have any women or children following, had the soldiers carrying their own armour and limited support followers to one for every three soldiers.
If you want to know the detailed assumptions he made, it's worth reading the book. Just for the record, here are the key assumptions made:
• Each soldier requires the nutritional equivalent of 3 lb of grain and 2 quarts of water per day (and I'll let you convert that to metric*),
• Each horse or mule would require forage of 10 lbs of chaff or straw plus 10 lb of grain per day and 8 gallons (32 quarts) of water per day,
• The average pack animal can carry 250 lb while the average soldier can carry up to 80 lbs of food and equipment,
• One pack animal was required for every 50 combatants to carry noncomestibles i.e. items such as tents and other camp necessities.
If you'd like to check how these were calculated and estimated, you will need to refer back to Engels (1978, pp. 11-25 plus Appendix 1:Rations).**
Having answered that question, one can then ask other questions based upon different availabilities of food and water along the way as well as the capacity of a logistics support system to bring the food to the soldiers. This is where the importance of naval supply vessels becomes critical. Alexander the Great controlled the sea sufficiently to bring food supplies in from other regions using ships. Knowing that Athens controlled the grain supply from the Black Sea to the Mediterranean and that Athens was an ally (no matter how reluctantly) of Alexander the Great means that the range of his army could be extended greatly. Ships are much more efficient than pack animals in carrying food supplies and water.
The battle at Issus was fought in November 333BC. Food supplies would have been limited at that stage if foraged from the land. The next crops would be in five to six months time, in the Spring of 332BC. Had Alexander moved inland, he would have had difficulty finding sufficient food for his army in hostile territory. He was far better off moving along the coast, capturing cities along the way and securing some food supplies that way while using the naval forces to provide grain from what can only be assumed was from the Black Sea. By moving towards Egypt, Alexander was also securing one of the few regions able to provide a surplus of food for the Persian Empire as well. He was cutting off a vital resource. (There were political reasons for doing so as well. Alexander would have known that the Persians had alienated the local population in Egypt by desecrating their temple of the sacred calf, providing him with an opportunity to overthrow the Persian governors and tax tributes).
Alexander left Egypt in the middle of 331BC (i.e. when he had secured food supplies from the recent harvest and was able to move into the heart of the Persian Empire having consolidated his position in Egypt). The battle at Gaugamela (modern day Irbil in Iraq) was held on October 1st 331BC. The distance between Alexandria in Egypt and is about 870 miles (or 1400 km). Engels (Appendix 5, pp.153) has calculated the fastest the army could have moved as 20 miles per day. So, at breakneck speed and allowing for no opposition it would have required 44 days with no rest to make that journey (never a realistic assumption). At least half, if not more, of that distance is traveling inland from the coast depending upon the route actually taken. It would have required a strong local knowledge of food and water supplies to ensure that the army of Alexander the Great would arrive in a fit condition to fight. That also assumes that Alexander knew where they would be fighting in advance of leaving Egypt.
Of course, a large army of 40,000 infantry and 7,000 cavalry (Wikipedia, 2007) is unlikely to move that fast anyway and it is likely at each step of the way inland, Alexander had to secure the territory to ensure his retreat was also protected (just in case). During the journey inland Alexander the Great had the viceroy of Syria (named as Arrimas) removed for failing to collect supplies needed for the inland journey (Engels, 1978 pp.66).
The interesting point is that while Alexander had lost the logistics advantage of being supplied by sea vessels once he left the Mediterranean coast, he still had the advantage of travelling much faster than the Persian army could for the reasons mentioned earlier in this blog i.e. no women and children and fewer support personnel. It was only after the battle of Gaugamela that Alexander allowed the army to have women and children following in the baggage train. That was when he had essentially captured one half of the Persian Empire (from Egypt through to modern Iraq) and all that remained was modern day Iran, Afghanistan and parts of modern Pakistan.
The next time that Alexander used ships to transport food was in the march from the Indus back to Persepolis through the deserts of Southern Iran. The plan was breathtakingly simple in concept and obviously difficult but not impossible in practice. Water would be supplied by the troops to the fleet and the fleet would provide food to the troops. However, the very monsoon supplying the water was the reason why the fleet was unable to sail until October, and the detailed preparation was in vain. (For more information, you must read Engels pp. 110 - 117). That Alexander the Great found a way though was a tribute to his ability to take risks and knowledge of logistics. Far from being irrational, he showed the greatest courage of his career in making those decisions.
At this stage I am not aware of any follow-up studies to the work of Engels but I'm happy to receive information on more recent studies that support or cast doubt on the findings.
Why are these findings about the importance of logistics and geography to the military strategy of Alexander the Great so important? They go to the very heart of Alexander's state of mind during these campaigns, especially the campaigns through the Gedrosian Desert and Southern Iran. It has been suggested that Alexander the Great was already "unstable" of mind at the time and that the campaigns were a a way of punishing the Macedonian soldiers who had effectively revolted in the Indus Valley campaigns against going further into India. Certainly he would have been very disappointed and angry, but his actions take on a very different light given the logistic and geographic situations he was facing and the possibility he had received disturbing news from Persia about the behaviour of his satrapal appointees.
That has to be the topic for another blog. I have some more research to do now :-) as this new insight demands investigation.
Notes:
* OK, 3 lb is equivalent to 1.4 kg approximately and 2 quarts (US) approximately equal 1.9 liters of water.
** You'll also want to know that a ship can carry 53,360 gallon of water plus the weight of the amphorae (Engels, 1978 pp. 58 n.26). That's 202,768 litres of water by volume or a weight of 202,786 kilograms.
Bibliography:
Cities located close to Alexandria, Egypt http://www.timeanddate.com/worldclock/distances.html?n=426 (read 07 April 2007)
Engels, Donald W. Alexander the Great and the Logistics of the Macedonian Army University of California Press, 1978
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