In the years between the First and Second World War, many nations developed early self-propelled artillery weapons. This was usually done by simply mounting a howitzer on a modified tank chassis (often making use of obsolete tanks for this purpose), but some designs also had purpose-built chassis. By the time war began, most Allied nations had fielded some form of self-propelled artillery, and many more were produced during the war. The most common configuration was a 155mm howitzer mounted on a lightly armoured tracked chassis, firing ballistic HE rounds. Allied commanders generally used it to bombard enemy bases and fortifications, but it was also highly effective as a long-range antipersonnel weapon. Although effective against Soviet defenses, Tesla coils had even greater range than art