Example – Resilience in Ancient Cities: The Eight-Year Siege of Constantinople
From 1394 to 1402 AD, the Turkish army led by Bayezid I besieged Constantinople, the capital of the Byzantine Empire. The city is strategically placed at one end of the Bosporus Strait, which connects the Black Sea and the Mediterranean (Figure 8). As such, it was of vital importance to the Byzantines. It had been besieged by many armies before then, including in the years 674-678, 714, 813, 1191, and 1204. The eight-year siege by Bayezid was the toughest test of the city’s resilience up to that date.
Constantinople survived the siege by Bayezid, which ended in 1402. How can a city containing tens of thousands of people survive a blockade for eight years, cut off from the outside world and living only on what they can produce on their own? A city needs more than strong fortifications to survive such an ordeal. It must foster complex and resilient food systems and water storage, building diverse sources into the system to ensure that it does not fail (Figure 9). How many modern cities could survive for eight years if all outside food supplies were cut off? The persistence of Constantinople in the face of so great a challenge is a true testament to its resilience.
Lastly, no city can withstand a siege without fresh water. Although its supply lines were cut off, Constantinople survived for eight years. How did the people have enough water to drink and grow crops? The River Lycos runs through the city, but that river alone was not sufficient to provide for the city as it grew. Several major aqueducts were built over the centuries to bring in water from nearby mountains and augment the water supply. In addition, cisterns and reservoirs were constructed within the city’s walls for long-term storage and protection of the water supply. During the eight-year siege, the city’s water supply never ran out—proof of its resilient design.
Not only did Constantinople have a complex system of food production in place by the time of the eight-year siege, it retained institutional knowledge gained from centuries of learning. The city held a repository of historical records that documented the agronomical history of the region, including texts describing what crops to grow and how to grow them, information on the seasons and movements of celestial bodies, manuals for animal husbandry, and other resources. Access to such an extensive library of knowledge was a valuable addition to the resilience of the city, as it documented the historic highs and lows the city had experienced and the adaptations of the populace to outside pressures. This allowed the citizens to learn and adapt from past triumphs and failures.
First, many granaries were constructed throughout the city. Excess grain was stored in these granaries so that the city could rely on them in lean times or when supply lines were cut off. Second, utilization of nearby fishing grounds helped supplement the city’s diet. Its close proximity to the Golden Horn—a prime fishery along the migration route of many species of nutritious fish such as tuna and bonito—meant that even poor townspeople could acquire high-quality sources of protein. Third, by increasing its control over agricultural lands and pasturage, Constantinople began to produce its own staples, such as wheat, instead of relying on distant suppliers. Vast tracts of land outside the mighty Constantine and Theodosian Walls were utilized over the years as pasture and farming fields. In addition, household gardens were widespread within the city and even the poorest citizens could grow some food by tending their own kitchen garden.
Although a prime target for invading armies, the city’s persistence in repelling attackers helped to strengthen it, not weaken it. For example, grain imports from Egypt were a staple of Constantinople’s diet. However, when supply lines were disturbed or cut off during times of war, drought, or famine, these imports were no longer reliable. Such disturbances occurred throughout the city’s history. As a means of coping with such problems, the people of Constantinople devised multiple strategies to enhance food and water production.
Barthel, Stephan, and Christian Isendahl. "Urban gardens, agriculture, and water management: Sources of resilience for long-term food security in cities." Ecological Economics 86 (2013): 224-234.
Gray, S. A., Gray, S., Cox, L. J., & Henly-Shepard, S. (2013). Mental Modeler: A fuzzy-logic cognitive mapping modeling tool for adaptive environmental management. Proceedings of the Annual Hawaii International Conference on System Sciences, 965–973. https://doi.org/10.1109/HICSS.2013.399