They were the most common type of watch from their development in the 16th century until wristwatches became popular afterWorld War I during which a transitional design, trench watches, were used by the military. Pocket watches generally have an attached chain to allow them to be secured to a waistcoat, lapel, or belt loop, and to prevent them from being dropped. An early reference to the pocket watch is in a letter in November 1462 from the Italian clockmaker Bartholomew Manfredi to the Marchese di Mantova Federico Gonzaga,where he offers him a "pocket clock" better than that belonging to the Duke of Modena. By the end of the 15th century, spring-driven clocks appeared in Italy, and in Germany. Peter Henlein, a master locksmith of Nuremberg, was regularly manufacturing pocket watches by 1524. Thereafter, pocket watch manufacture spread throughout the rest of Europeas the 16th century progressed. Early watches only had an hour hand, the minute hand appearing in the late 17th century.The first American pocket watches with machine made parts were manufactured by Henry Pitkin with his brother in the later 1830s.