▁On ▁ 6 ▁August ▁ 1 4 3 9 ▁the ▁Ott oman ▁forces ▁under ▁I sh ak - B eg ▁defeated ▁Ser bian ▁forces ▁near ▁Nov o ▁Br do . ▁The ▁Ott om ans ▁captured ▁S med ere vo ▁on ▁ 1 8 ▁August ▁ 1 4 3 9 ▁which ▁reduced ▁the ▁territory ▁of ▁the ▁Ser bian ▁Desp ot ate ▁to ▁Z eta ▁and ▁a ▁region ▁around ▁Nov o ▁Br do . ▁The ▁forces ▁under ▁Mur ad ▁II ▁joined ▁I sh ak - B eg ▁to ▁attack ▁Nov o ▁Br do , ▁but ▁its ▁g arrison ▁successfully ▁rep elled ▁their ▁attacks . ▁The ▁Ott om ans ▁realized ▁that ▁it ▁would ▁be ▁difficult ▁to ▁capture ▁the ▁well - def ended ▁Nov o ▁Br do , ▁so ▁Mur ad ▁II ▁ordered ▁for ▁retre at ▁and ▁a ▁stay ▁in ▁Sk op je ▁during ▁the ▁winter . ▁Before ▁they ▁did ▁so , ▁they ▁ro bb ed ▁car av ans ▁of ▁R ag us an ▁mer ch ants , ▁while ▁Mur ad ▁II ▁went ▁to ▁Ad rian ople . ▁The ▁Ott om ans ▁allowed ▁Gr g ur ▁B rank ović ▁to ▁govern ▁his ▁father ' s ▁former ▁est ates ▁in ▁southern ▁Ser bia , ▁as ▁Ott oman ▁v ass al . ▁During ▁spring ▁and ▁summer ▁of ▁ 1 4 4 0 ▁the ▁Ott om ans ▁again ▁bes ie ged ▁Bel grade , ▁with ▁can n ons ▁cast ▁in ▁S med ere vo ▁captured ▁a ▁year ▁before , ▁but ▁without ▁success . ▁ ▁Sie ge ▁▁ ▁In ▁ 1