▁he ▁discussed ▁philosophy ▁and ▁government ▁policies . ▁He ▁us her ed ▁in ▁a ▁cultural ▁golden ▁age ▁that ▁riv aled ▁Se j ong ' s ▁reign ▁by ▁publishing ▁numerous ▁books ▁on ▁ge ography , ▁eth ics , ▁and ▁various ▁other ▁fields . ▁ ▁He ▁also ▁sent ▁several ▁military ▁campaign s ▁against ▁the ▁J urch ens ▁on ▁the ▁northern ▁border ▁in ▁ 1 4 9 1 , ▁like ▁many ▁of ▁his ▁prede cess ors . ▁The ▁campaign , ▁led ▁by ▁General ▁He o ▁J ong , ▁was ▁successful , ▁and ▁the ▁defeated ▁J urch ens , ▁led ▁by ▁the ▁U d ige ▁cl an ▁( ), ▁retre ated ▁to ▁the ▁north ▁of ▁the ▁Y alu ▁River . ▁King ▁Se ong j ong ▁was ▁succeeded ▁by ▁his ▁son , ▁Ye ons ang un , ▁in ▁ 1 4 9 4 . ▁ ▁Liter ati ▁p urg es ▁ ▁Ye ons ang un ▁is ▁often ▁considered ▁the ▁worst ▁t yr ant ▁of ▁the ▁Jose on , ▁whose ▁reign ▁was ▁marked ▁by ▁Korean ▁liter ati ▁p urg es ▁between ▁ 1 4 9 8 ▁and ▁ 1 5 0 6 . ▁His ▁behavior ▁became ▁err atic ▁after ▁he ▁learned ▁that ▁his ▁bi ological ▁mother ▁was ▁not ▁Queen ▁Jung h ye on ▁but ▁the ▁de posed ▁Queen ▁Lady ▁Y un , ▁who ▁was ▁forced ▁to ▁drink ▁poison ▁after ▁poison ing ▁one ▁of ▁Se ong j ong ' s ▁conc ub ines ▁out ▁of ▁je alous y ▁and ▁leaving ▁a ▁scratch ▁mark ▁on ▁Se ong j ong ' s ▁face