 Complete the following phrase:  He was taken captive in July 1384 by Vytautas, Grand Duke of Lithuania, after Vytautas reconciled with his cousin Jogaila during the Lithuanian Civil War 13811384. At the time Marquard was a castellan of New Marienburg, a Teutonic Castle on the Neman River. Marquard became a friend and close adviser of Vytautas, who sent him on diplomatic missions to establish alliance with the Knights when 