Al-Hassan interprets Ibn Khaldun as reporting the use of cannon as siege machines by the Marinid sultan Abu Yaqub Yusuf at the siege of Sijilmasa in 1274. Super-sized bombards were used by the troops of Mehmed II to capture Constantinople, in 1453. Urban, a Hungarian cannon engineer, is credited with the introduction of this cannon from Central Europe to the Ottoman realm. It could fire heavy stone balls a mile, and the sound of their blast could reportedly be heard from a distance of . A piece of slightly later date (see pic) was cast in bronze and made in two parts: the chase and the breech, which, together, weighed 18.4 tonnes. The two parts were screwed together using levers to facilitate the work.