ged ▁tor ped o ▁tub es . ▁ ▁Her ▁main ▁arm ored ▁bel t ▁was ▁ ▁thick ▁in ▁the ▁central ▁portion , ▁and ▁was ▁composed ▁of ▁Kru pp ▁c ement ed ▁arm or ▁( K CA ). ▁Her ▁main ▁battery ▁gun ▁tur rets ▁were ▁protected ▁by ▁the ▁same ▁thick ness ▁of ▁K CA ▁on ▁the ▁sides ▁and ▁faces , ▁as ▁well ▁as ▁the ▁bar b ettes ▁that ▁supported ▁the ▁tur rets . ▁Ost f ries lands ▁deck ▁was ▁ ▁thick . ▁ ▁Service ▁history ▁ ▁Ost f ries land ▁was ▁ordered ▁by ▁the ▁German ▁Imperial ▁Navy ▁( K ais er liche ▁Marine ) ▁under ▁the ▁prov is ional ▁name ▁Er s atz ▁Old enburg , ▁as ▁a ▁replacement ▁for ▁the ▁old ▁coast al ▁defense ▁ship ▁. ▁The ▁contract ▁for ▁the ▁ship ▁was ▁awarded ▁to ▁the ▁Kaiser liche ▁Wer ft ▁( Im per ial ▁D ock yard ) ▁in ▁Wilhelm sh aven ▁under ▁construction ▁number ▁ 3 1 . ▁Work ▁began ▁on ▁ 1 9 ▁October ▁ 1 9 0 8 ▁with ▁the ▁lay ing ▁of ▁her ▁ke el , ▁and ▁the ▁ship ▁was ▁launched ▁less ▁than ▁a ▁year ▁later , ▁on ▁ 3 0 ▁September ▁ 1 9 0 9 . ▁She ▁was ▁christ ened ▁by ▁the ▁Princess ▁of ▁Inn hausen ▁and ▁K ny ph aus en , ▁a ▁representative ▁of ▁the ▁oldest ▁East ▁F ris ian ▁nob ility . ▁F itting - out , ▁including ▁completion ▁of ▁the ▁super structure ▁and ▁the ▁installation ▁of ▁arm ament , ▁last ed ▁until ▁August ▁