Winter operations 1914–1915
A German offensive began on 21 October but the 4th Army ( Albrecht , Duke of Württemberg ) and 6th Army ( Rupprecht , Crown Prince of Bavaria ) were only able to take small amounts of ground , at great cost to both sides , at the Battle of the Yser and further south in the First Battle of Ypres 
<triplet> First Battle of Ypres <subj> Albrecht, Duke of Württemberg <obj> participant <subj> Rupprecht, Crown Prince of Bavaria <obj> participant