The Yatagan (yatağan) makes its appearance in the second half of the 16th century, and is an infantry weapon in which the hilt is generally made of bone or ivory and the pommel is flared.The sword of Sultan Mehmed II illustrates its basic form with its slightly curved blade that thickens at the back.During the reigns of the sultans Bayezid II and Suleiman the Magnificent, the kilij attained its classic form, becoming shorter, lighter, and straighter.In the siege of Baghdad where the Ottomans retook the city from the Persians (1638), gunners of European descent served on the lines.[5] Although the payroll registry records were not good at keeping up with the number of gunners because the comrades of those deceased collected the money on their behalf.To add to this the 16th century brought the latest technical advancements in gun making to the Ottomans; in the form of Jews fleeing from the Spanish Inquisition.Although such weapons being primarily used in sieges; where they were cast on site due to the logistical difficulties attributed to transport them there, they were used as late as 1809 when massive stone-firing guns were used with some effect against British ships during the Dardanelles Operation, throwing 1000-1,000 lb (450 kg) marble with a range of 1 mi (1.6 km).The Fall of Constantinople was perhaps "the first event of supreme importance whose result was determined by the use of artillery", when the huge bronze cannons of Mehmed II breached the city's walls, ending the Byzantine Empire, according to Sir Charles Oman.[11] Mehmed II erected many cannon-foundries in Istanbul, the most famous of which is the Tophane foundry which produced bronze cannons for siege warfare.