All sides had signed the Hague Conventions of 1899 and 1907, which prohibited the use of chemical weapons in warfare. In 1914, there had been small-scale attempts by both the French and Germans to use various tear gases, which were not strictly prohibited by the early treaties but which were also ineffective. The first use of more lethal chemical weapons on the Western Front was against the French near the Belgian town of Ypres. The Germans had already deployed gas against the Russians in the east at the Battle of Bolimów.