Most of the Red Cross POW records are available to view free online. These documents are gold dust in helping research ancestors who were taken prisoner because they give excellent information eg. name, Regiment, Battalion, Company, date and place captured and next of kin details (details varies). If your ancestor was captured then you can pinpoint him to his company and therefore would be able to cross reference via the Battalions war diaries.
This is the links:
http://grandeguerre.icrc.org/This link explains how best to use the above website:
http://www.1914-1918.net/soldiers/icrc.htmlAny help just ask
Regards
Adrian