▁a ▁Pacific ▁island ▁people , ▁come ▁from ▁the ▁journal ▁of ▁Antonio ▁P ig af etta , ▁the ▁expedition ' s ▁scri be ▁and ▁one ▁of ▁only ▁ 1 8 ▁crew ▁members ▁to ▁eventually ▁surv ive ▁the ▁circ umn avigation ▁of ▁the ▁glo be , ▁completed ▁by ▁Juan ▁Sebastian ▁El cano . ▁ ▁Spanish ▁colon ization ▁ ▁Despite ▁Mag ellan ' s ▁visit , ▁Gu am ▁was ▁not ▁officially ▁claimed ▁by ▁Spain ▁until ▁ 1 5 6 5 ▁by ▁Miguel ▁L ope z ▁de ▁Leg az pi . ▁However , ▁the ▁island ▁was ▁not ▁actually ▁colon ized ▁until ▁the ▁ 1 7 th ▁century . ▁On ▁June ▁ 1 5 , ▁ 1 6 6 8 , ▁the ▁g alle on ▁San ▁Diego ▁arrived ▁at ▁the ▁shore ▁of ▁the ▁island ▁of ▁Gu am . ▁Jes uit ▁mission aries ▁led ▁by ▁P adre ▁Diego ▁Luis ▁de ▁San ▁V itor es ▁arrived ▁on ▁Gu am ▁to ▁introduce ▁Christian ity ▁and ▁develop ▁trade . ▁The ▁Spanish ▁taught ▁the ▁Cham or ros ▁to ▁cultiv ate ▁ma ize ▁( c orn ), ▁raise ▁cattle , ▁and ▁tan ▁h ides , ▁as ▁well ▁as ▁to ▁adopt ▁western - style ▁cl othing . ▁They ▁also ▁introduced ▁the ▁Spanish ▁language ▁and ▁culture . ▁Once ▁Christian ity ▁was ▁established , ▁the ▁Catholic ▁Church ▁became ▁the ▁foc al ▁point ▁for ▁village ▁activities , ▁as ▁in ▁other ▁Spanish ▁cities . ▁Since ▁ 1 5 6 5 , ▁Gu am ▁became ▁a ▁regular ▁port - of - call ▁for ▁the ▁Spanish ▁g alle ons ▁that ▁crossed