So I have a story where a disaster triggered a series of Civil Wars in different countries and now many countries live without law and in constant danger due to conflicts and violence.

How long it would take for a city like Moscow to collapse if it were under siege ?

  • This siege is preventing any supply from entering the city.
  • No one gets in or out of the city, except the Government Military.
  • Not all residents support the rebels who took the town and are suffering from theft and lack of security.
  • No other country will help/end the conflicts because they are suffering from the same kind of uprisings.
  • $\begingroup$ I think Napoleon tried once. Winter was coming. $\endgroup$
    – Kii
    Dec 7, 2015 at 20:06
  • $\begingroup$ "No one gets in or out of the city, except the Military" - is this the rebel military, or the siege military? The people seiging should prevent people getting into the city (with supplies, etc), while the people in control of the city should prevent the sieging people getting in - so I find it hard to believe much of anybody is getting in, and that there would be heavy vigilance for the people getting out. (Maybe they have info or are spys) $\endgroup$ Dec 7, 2015 at 20:11
  • $\begingroup$ Also, the fact that the streets are a battlefield suggests the city is already collapsed/collapsing? I don't quite follow the setup and question. $\endgroup$ Dec 7, 2015 at 20:14
  • 1
    $\begingroup$ I edited the question. The idea is government forces are besieging the city preventing anyone leaving. $\endgroup$
    – Gabriel
    Dec 7, 2015 at 20:33
  • $\begingroup$ What do you mean by collapse? All inhabitants dead or surrendered? No structure left standing? Invading army controls the city? What era/ setting is this in. What weapons and supplies do both sides have? $\endgroup$ Dec 8, 2015 at 5:36

4 Answers 4


As a baseline for how long a besieged city can survive being essentially cut off from the world, I would point you to the Siege of Leningrad.

At the end of a three year siege with very limited resupply, the population of the city diminished from a pre-war population of ~3 million to approximately 700,000 - with roughly half that number being soldiers who came to help Leningrad.

Another baseline would be the ongoing Battle of Aleppo, which has been going on for approximately three years. At this point, the rebels and government forces control their own areas, and barring outside intervention will likely remain in an extended stalemate.

  • $\begingroup$ There is a big difference between limited resupply and preventing any supply from entering the city (OP). The latter quickly becomes devastating. I don't think any modern city has food reserves that last longer than a few months. And depending on the climate cutting of fresh water supply might have an even more drastic effect. $\endgroup$
    – fgysin
    Dec 8, 2015 at 10:45

Factors that influence length of seige:

A: Water Supply. If there are springs or wells internally, then water is not the limiting factor. If water is stored, then when the water is gone, soon the city falls. The degree of water also is important: Water for firefighting?

B: Food supply. If you are willing to eat boring food, you can easily store years worth. Wheat runs 60 lbs/bushel -- roughly the same density as water. So a 55 gallon drum is close to 500 lbs. The romans marched back and forth on 2 lbs grain per man per day. In a seige situation non-physical workers could subsit on 1.25. Without fresh food you would have various deficiency diseases. Some grains may develope Vit C on sprouting. Would need to check that.

C: Hygiene. MANY seiges have broken one way or another when one side got sick. Cholera and typhoid are the ones that spring to mind. I think I read somewhere that a fighting man in medieval time was several times more likely to die from disease as from battle.

D: Organization: Every usable container is filled with water and positioned to put out fires. Rationing. Hygiene rules. Conserving everything that might be useful. Weapons from anthing: Catapults taht shoot roof tiles. Doors backed by a space with notches in the walls, timbers nearby. If it looks like the gate is under assault, put timbers in the notches and fill the space between timber and gate with rubble.


It is not a complete answer but I would like to point two things that have not been mentioned so far. Based on the Taiping rebellion.

  1. Agriculture inside the city: Nanjing, the capital of the Heavenly kingdom decided to destroy parts of the city to grow food. The population of the city and the surrounding regions had been reduced by more than a decade of war. Many people have fled or died. The authorities decided to destroy unoccupied parts of the city to make room for agriculture. It looked promising but the Qing launched an assault and killed tens of thousands. If it hadn't been of this, the city might have survived longer. But the city already endured more than a decade of war, including several months of siege.
  2. Cannibalism: Several British correspondents reported that human flesh was being sold in the markets in Anqing and in the province of Anhui. I can't be sure if this is true or just colonialist propaganda but the besieged could survive longer by doing this.
  • $\begingroup$ Cannibalism will only marginally extend the life of a seige. Bodies diminish, but hunger recurs. $\endgroup$
    – Oldcat
    Dec 8, 2015 at 18:41

The fastest killer is the water supply. In absence of rain, underground water, channels or rivers a city wouldn't last more than three days in the worst case.

A corolary of this is related to energy, a modern city without fuels won't have energy for more than a week, which means that after a short time water won't be available if you can't pump it.


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