In spite of the singular freedom of England from invasion the English have constantly been overwhelmed with panic, fearing the worst which never came. In 1335 an alarm was raised of a French invasion. The King at the beginning of August wrote to order all men between sixteen and sixty to be arrayed, and a Council to be immediately held in London. Leaders of the Londoners were appointed who were to defend the city in case the enemy landed. Again in 1370 preparations were made for an expected attack upon the city, and in 1383 false reports were circulated from the war in Flanders, for the circulation of which an impostor was punished.[26] Three years later the citizens were in great terror on account of a widespread report that the French King was about to invade England. There seems to have been something in the report, because Harry Hotspur believed it, and having waited impatiently for the French King to besiege Calais, returned to England to meet him here. Stow, however, was very satirical about the English fears. He wrote: 'The Londoners, understanding that the French King had got together a great navie, assembled an armie, and set his purpose firmely to come into England, they trembling like leverets, fearefule as mise, seeke starting holes to hide themselves in, even as if the citie were now to bee taken, and they that in times past bragged they would blow all the Frenchmen out of England, hearing now a vaine rumour of the enemies comming, they runne to the walles, breake downe the houses adjoyning, destroy and lay them flat, and doe all things in great feare, not one Frenchman yet having set foote on shipboard, what would they have done, if the battell had been at hand, and the weapons over their head.'[27]
No improvement in the condition of houses in London appears to have taken place until long after the Conquest, and the low huts, closely packed together, which filled the streets during the Saxon period, were continued well into the thirteenth century. These houses were wholly built of wood, and thatched with straw, or reeds.
All mediæval cities were fatally liable to destruction by fire, but London appears to have been specially unfortunate in this respect. In the first year of the reign of Stephen a destructive fire spread from London Bridge to the Church of St. Clement Danes, destroying St. Paul's in the way. This fire caused some improvements in building, but special regulations were required, and one of the early works undertaken by the newly established 'Commune' was the drawing up, in 1189, of the famous Assize of Building, known by the name of the first Mayor as Fitz-Ailwyne's Assize.