There was a recoinage due to debasement of the old coinage. This increased the number of coins in circulation. The price of wheat went from about 7s. in 1270 to about 5s. per quarter in 1280. Also the price of an ox went from 14s. to 10s. Then there were broad movements of prices, within which there were wide fluctuations, largely due to the state of the harvest. From 1280 to 1290, there was runaway inflation. In some places, both grain and livestock prices almost doubled between 1305 and 1310. Wheat prices peaked at 15s.5d. a quarter in the famine year of 1316. In 1338, prices dropped and remained low for twenty years. The poor were hurt by high prices and the lords of the manors were hurt by low prices. As before, inadequate care and ignorance of nutrition caused many infant deaths. Accidents and disease were so prevalent that death was always near and life insecure. Many women died in childbirth. Edward I always sought the agreement of Parliament before assembling an army or taking actions of war, and Parliamentary consent came to be expected for such. He completed the conquest and annexation of Wales in 1284. The feudal army was summoned for the last time in the 100 year war with France, which began in 1337. In it the English longbow was used to pierce French knights' armor. There had been much competition between the strength of arrows to pierce and the heaviness of armor to resist. Guns and cannon with gunpowder were introduced in 1338. A system to raise an army by contract was developed. Contracts were made with nobles, knights, or esquires who undertook to enlist an agreed number of armored men-at-arms and archers, who were paid wages. The King provided transport for each contractor and his retinue, baggage, and horses. The title of "knight" now resumed its military character as well as being a social rank. After Edward I died in 1307, there was a period of general lawlessness and contests for power between earls and barons and the irresponsible King Edward II, who was not a warrior king. He eventually was assassinated. Also in 1307, Parliament required the king to obtain its consent for any exchange or alteration of the currency. By 1319, the guilds of London had become so powerful that they extracted a charter from the king that to be a citizen of London one had to be a member of a guild. By 1326, scholars, the nobility, and the clergy had reading eyeglasses, which had been invented in Italy, probably by the glass blowers. Italy was famous for its glasswork. The first eyeglasses were fabricated by pouring molten glass into curved molds. The actual shape was difficult to control because thermal expansion and contraction resulted in bubbles and other optical imperfections. As of 1336, importing foreign cloth or fur, except for use by the King's family, was prohibited, as was the export of unwoven wool. Later, this was relaxed and a customs tax of 33% was imposed on wool exported.