Sickness could be a huge problem for any medieval army. With thousands of men living close together, and no modern medicine, disease ran rampant.
Disease was particularly deadly in the enclosed confines of a town or castle under siege. With the bodies piling up, the defenders could not get away from the sickness. Without our modern understanding of germs, there was no way of combatting the problem. Attackers sometimes encouraged such sickness by flinging dead animals or disease ridden corpses over the walls. At the Siege of Rouen in 1418-19 the English threw dead animals down wells to contaminate the city’s water supply.
Disease could also be a problem for attackers. Outbreaks in the Crusader camp besieging Acre in 1189-91 killed many men and severely weakened the attacking force.
Horrifying as they could be, assaults were often the best way for attackers to end a siege. If time was pressing, or the defenders showed no signs of running out of supplies, then an all out attack could lead to a swift victory. Scottish King Robert the Bruce is reported to have led an assault across a flooded moat during his campaign against the English occupiers.
If bombardments or undermining had breached the walls then any assault would be through these gaps. If not then attackers had to assault the battlements from ladders, while rocks and other missiles fell on their heads, or approach from the rarer but safer confines of a siege tower.
Despite all the military tactics available, the most successful sieges were those that ended with talking. Starvation was a gruelling prospect for the defenders, and assault equally unappealing to the attackers. Under accepted rules of war, a town captured by force could be ransacked but one that surrendered could not. This encouraged agreements to surrender if the defenders were not relieved within a set amount of time. This, rather than an assault, ended some of the most significant sieges, such as Stirling in 1304 and Harfleur in 1415.
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