▁by ▁the ▁time ▁work ▁actually ▁began ▁on ▁the ▁ship , ▁she ▁had ▁been ▁completely ▁red es igned . ▁Leipzig ▁was ▁significantly ▁larger ▁than ▁Fre ya ; ▁her ▁increased ▁size ▁allowed ▁for ▁a ▁substantial ly ▁stronger ▁gun ▁battery , ▁a ▁more ▁powerful ▁prop ulsion ▁system , ▁and ▁more ▁sp a cious ▁crew ▁qu arters , ▁which ▁proved ▁to ▁be ▁very ▁useful ▁on ▁extended ▁voy ages ▁over se as . ▁Another ▁major ▁advance ▁was ▁the ▁use ▁of ▁iron ▁to ▁build ▁the ▁ships ' ▁h ull s ▁instead ▁of ▁traditional ▁tim ber ▁frames ▁and ▁pl ank ing . ▁Although ▁earlier ▁vessels ▁had ▁been ▁intended ▁to ▁serve ▁as ▁fleet ▁sc outs , ▁by ▁the ▁time ▁Leipzig ▁and ▁Prin z ▁Ad al bert ▁entered ▁service ▁in ▁the ▁mid - 1 8 7 0 s , ▁the ▁w ides p read ▁ad option ▁of ▁iron cl ad ▁war ships ▁in ▁European ▁nav ies ▁meant ▁that ▁such ▁use ▁was ▁imp ract ical , ▁since ▁un arm ored ▁war ships ▁would ▁be ▁useless ▁against ▁arm ored ▁oppon ents . ▁This ▁fact ▁was ▁most ▁clearly ▁demonstrated ▁by ▁the ▁Battle ▁of ▁Pac och a ▁between ▁Britain ▁and ▁Peru ▁in ▁ 1 8 7 7 . ▁As ▁a ▁result , ▁the ▁Leipzig ▁class ▁was ▁to ▁be ▁used ▁sole ly ▁as ▁over se as ▁cru is ers . ▁ ▁The ▁ships ▁went ▁on ▁two ▁cru ises ▁each ▁in ▁the ▁late ▁ 1 8 7 0 s ▁and ▁early ▁ 1 8 8 0 s , ▁primarily ▁to ▁East ▁Asia . ▁In ▁ 1 8 7