As it was always an object to the besiegers of a town to start a conflagration if they could, Greek fire was used for the purpose. The flame of this fearfully destructive liquid, the composition of which is doubtful, could not be quenched by water. It was placed in round earthenware vessels that broke on falling, and which were shot from catapults; as the roofs of ancient and mediæval dwelling-houses were usually thatched, it of course dealt destruction when it encountered such combustible material.
The successful attack or defence of a fortified town often depended on which of the armies engaged had the more powerful balistas, catapults or trebuchets, as one engine of superior range could work destruction unimpeded if it happened that a rival of similar power was not available to check its depredations.
Froissart relates that ‘at the siege of Mortagne in 1340, an engineer within the town constructed an engine to keep down the discharges of one powerful machine in the besieging lines. At the third shot he was so lucky as to break the arm of the attacking engine.’ The account of this incident, as given by Froissart, is so quaint and graphic that I quote it here: ‘The same day they of Valencens raysed on their syde a great engyn and dyd cast in stones so that it troubled sore them within the town. Thus ye firste day passed and the night in assayling and devysing how they might greve them in the fortress.
‘Within Mortagne there was a connying maister in making of engyns who saw well how the engyn of Valencens did greatly greve them: he raysed an engyn in ye castle, the which was not very great but he trymmed it to a point,[39] and he cast therwith but three tymes. The firste stone fell a xii[40] fro the engyn without, the second fell on ye engyn, and the thirde stone hit so true that it brake clene asonder the shaft of the engyn without; then the soldyers of Mortagne made a great shout, so that the Hainaulters could get nothing ther[41]; then the erle[42] sayd how he wolde withdrawe.’
[39] i.e. with great exactness or ‘to a hair.’
[40] A foot.
[41] Could not throw any more stones.
[42] Count of Hainault. He was besieging Tournay, but left that place and went to besiege Mortagne and ordered the people of Valenciennes to go with him.
(From the translation made at the request of Henry VIII. by John Bourchier, second Lord Berners, published 1523–1525.)
These siege engines when only of moderate size were not always successful, as in some cases the walls of a town were so massively built that the projectiles of the enemy made little impression upon them. Froissart tells us that it was then the habit of the defenders of the walls to pull off their caps, or produce cloths, and derisively dust the masonry when it was struck by stones.