Its not certain when the Ottomans started using firearms, however its argued that they had been using cannons since the Battles of Kosovo (1389) and Nukap (1396) and most certainly by the 1420s. Some argue that field guns only entered service shortly after the Battle of Varna (1444) and more certainly used in the Second Battle of Kosovo (1448). Firearms, (especially grenades) were used in the 1683 siege of Vienna The arquebus reached them around 1425.