 Around 19 : 30 , Admiral John Jellicoe 's main force of battleships entered the battle ; Orion began firing at Markgraf at 19 : 32 ; she fired four salvos of 13 @.@ 5 @-@ inch Armor @-@ <unk> , <unk> ( <unk> ) shells and scored a hit with the last salvo . The shell exploded upon impacting the armor protecting the No. 6 15 cm gun casemate . The shell failed to penetrate but holed the armor and disabled the gun . The explosion seriously injured two and killed the rest of the gun crew . A heavy shell nearly struck the ship at the same time , and at 19 : 44 , a bent propeller shaft forced Markgraf 's crew to turn off the port engine ; naval historian John Campbell speculated that this shell was the one that damaged the shaft . Her speed dropped to 17 or 18 kn ( 31 or 33 km / h ; 20 or 21 mph ) , though she remained in her position in the line . 
