third battle of Ypres

third battle of Ypres
    n 1: battle in World War I (1917); an Allied offensive which
         eventually failed because tanks bogged down in the
         waterlogged soil of Flanders; Germans introduced mustard
         gas which interfered with the Allied artillery [syn:
         {Ypres}, {battle of Ypres}, {third battle of Ypres}]