How were fortification doors protected against fire?

Question

Ancient and medieval fortifications are often shown to have wooden gate doors in the midst of their stone walls. Now granted, these doors are often massive and incredibly thick, but it still seems like a very risky point of weakness for an otherwise imposing structure. A splash of oil and a flaming arrow seems like it could leave your castle with a giant gaping hole in the wall in a matter of hours.

And yet, that didn't seem to happen. Or at least not regularly enough to require a different method of constructing doorways through the ages. Attacking armies often had to bash down the gates with rams, or scale the walls rather than going through the gates at all, to get inside a city, castle, or fort.

Why was that? What methods were used to protect the wooden elements of fortifications against fire? I've heard of siege towers being covered by animal skins for that purpose, but never fortification doors. And while thick doors like that would take a long time to burn through, it still seems like it would be vastly easier to splash some oil and throw a torch than to undertake more "conventional" siege methods.

Unless, as it seems, that wouldn't have worked?

Answer 1

Short answer is, they weren't, not specifically. The siege of Sion (the castle in Bohemia) is thought to have been decided by the gatehouse being burned down, but there the entire gatehouse structure was wooden rather than just the gate itself, and it took several months of bombarding the entire castle with fire arrows.

In general, protecting your gate from fire is done about the same way as protecting it from battering rams - you try to prevent the besiegers from getting too close using standard methods, like pelting them with arrows or dropping heavy things or hot liquid on them. And it works on general principle, since you need to be within a few meters of the gate to douse it in oil, and thick wooden beams do not easily burn through anyhow. Plus, it's not a very good idea to be bringing flammables to where you can yourself get hit by a fire arrow.

A more reliable way to exploit the relative structural weakness of a gate would be to aim your siege engines at it, but those were rather tricky to aim that precisely, at least before siege cannon were perfected. Plus, gates would often be constructed in such a way that even if they were breached, there would be a killing ground and possibly a second gate that the enemy would need to also breach to get inside (as seen at the Siege of Gawilghur).

Answer 2

This seems more like a technical question than a historical one, but anyway, "splash some oil and throw a torch" will not burn down a large door or any large piece of wood for that matter. Starting a fire requires a certain amount of heat, so you need a large mass of flammable tinder to get something started. The larger the door, the more tinder you will need. A splash of oil will not do it.

This being said, fire can be used against any exposed door or wooden structure in a siege. You make a large ball of rags and dry wood, set it on fire, then push it against the structure. As long as the fire ball is big enough you will burn down the target structure. This exact procedure was commonly followed in sieges throughout history. For example, in the American frontier Indians would often try to burn down block houses by gathering a big bundle of brush, piling it against a door or wall, and setting it on fire. The blockhouses had to keep water on hand to prevent this. They also had to have special ports for water and guns in the walls to make such an operation very dangerous for the attackers.

In large castles the standard method for preventing this kind of attack is to put an iron gate in front of the door. This prevents any accumulation of wood from being placed directly against the door. Also, such gates, like block houses, always have overhangs with down ports so that water can be poured down onto the gate.

Answer 3

I like to visit old castles and am lucky enough to live where there are quite a few.

If the old gate is still there you can see it was often covered in sheet metal. Some castles has skins stretched over the gates and would wet them to stop them catching fire. The doors were often set back inside the doorway so it wasn't easy to shoot at them.

Fire arrows have shorter range, and they cleared all trees and undergrowth away around the castle, so the defenders could shoot any attacking archers, as the defenders were shooting downwards they could shoot farther.

People in the old days were often very inventive.