After the end of World War I Poland seized large quantities of M1918 helmets. Most of those were later sold to various countries, including Spain. However, at the end of the 1930s it was discovered that the standard Polish wz. 31 helmet was unsuitable for tank troops and motorized units; while offering decent protection, it was too large and heavy. As a stop-gap measure before a new helmet was developed, the General Staff decided to issue M1918 helmets to the 10th Motorized Cavalry Brigade, which used them during the Polish Defensive War.