German observation post destroyed - Public domain map

Photograph shows a destroyed German observation post outside Oosttaverne Wood, Belgium on June 11, 1917, during the Battle of Messines during World War I. The British officer in the foreground is holding a German map board. (Source: Flickr Commons project, 2015 and similar image on the Imperial War Museums website: http://www.iwm.org.uk/collections/item/object/205078178)