▁killed ▁all ▁four ▁of ▁his ▁Queen ' s ▁brothers ▁and ▁his ▁son ▁Se j ong ' s ▁father - in - law . ▁T ae j ong ▁remains ▁a ▁controvers ial ▁figure ▁who ▁killed ▁many ▁of ▁his ▁riv als ▁and ▁relatives ▁to ▁gain ▁power ▁and ▁yet ▁ruled ▁effectively ▁to ▁improve ▁the ▁popul ace ' s ▁lives , ▁strength en ▁national ▁defense , ▁and ▁lay ▁down ▁a ▁solid ▁foundation ▁for ▁his ▁successor ▁Se j ong ' s ▁rule . ▁ ▁Se j ong ▁the ▁Great ▁ ▁In ▁August ▁ 1 4 1 8 , ▁following ▁T ae j ong ' s ▁ab dic ation ▁two ▁months ▁earlier , ▁Se j ong ▁the ▁Great ▁asc ended ▁the ▁throne . ▁In ▁May ▁ 1 4 1 9 , ▁King ▁Se j ong , ▁under ▁the ▁advice ▁and ▁guidance ▁of ▁his ▁father ▁T ae j ong , ▁emb ark ed ▁upon ▁the ▁Gi ha e ▁Eastern ▁Ex ped ition ▁to ▁remove ▁the ▁n uis ance ▁of ▁wa egu ▁( co ast al ▁pir ates ) ▁who ▁had ▁been ▁operating ▁out ▁of ▁Ts ush ima ▁Island . ▁ ▁In ▁September ▁ 1 4 1 9 , ▁the ▁da im y ō ▁of ▁Ts ush ima , ▁Sad am ori , ▁capit ulated ▁to ▁the ▁Jose on ▁court . ▁In ▁ 1 4 4 3 , ▁The ▁Tre aty ▁of ▁G ye ha e ▁was ▁signed ▁in ▁which ▁the ▁da im y ō ▁of ▁Ts ush ima ▁was ▁granted ▁rights ▁to ▁conduct ▁trade ▁with ▁Korea ▁in ▁fifty ▁ships ▁per