Passchendaele has become popular with the misery of grinding attrition warfare. This type of warfare was often fought in thick mud. The land between Dixmude and the river Lys was crossed by streams and ditches that were used for drainage. Most of these flowed west, moving towards the Ypres—Commines canal which went north-south. The land was flat and swampy but for good drainage. August 1917 was very cold and wet. This was not usual. Very big artillery strikes had also destroyed the ground surface. There were times where it was dry. It was most dry in September, but mud was still in parts of the battlefield. Tanks got stuck in mud and some soldiers and horses drowned in it.