 Complete the following phrase:  During the Interim Peace Finland began constructing Salpa Line to fortify the new border to replace Mannerheim Line fortifications. Salpa Line artillery included six 15245 C guns. In the Continuation War 15245 C was involved in the fighting again and several guns were lost to barrel explosions or simply worn out. Some guns lost in the Winter War were recaptured bringing the total to 78 pieces in 1943. By 1 May 1944 the number had dropped to 60. During World War II 15245 C guns were also used as anti-aircraft guns. The guns, designed originally before aircraft had been invented, were not especially effective in this role even after the modifications that had been done. Despite the limitations they were used against enemy bomber formations, especially in the 