World War I

 A German communications squad behind the Western front, setting up using a tandem bicycle power generator to power a light radio station in September of 1917    A German dog hospital, treating wounded dispatch dogs coming...

 A German communications squad behind the Western front, setting up using a 
tandem bicycle power generator to power a light radio station in September of 1917
  
 A German dog hospital, treating wounded dispatch 
dogs coming from the front, ca. 1918
  
 A German soldier holds the handset of a field telephone to his head, as two others 
hold a spool of wire, presumably unspooling it as they head into the field
  
 A German soldier throws a hand grenade against enemy 
positions, at an unknown battlefield during World War I
  
German soldiers flee a gas attack in Flanders, Belgium, in September of 1917