 Complete the following phrase:  Panzer IVs comprised around half of the available German tank strength on the Western Front prior to the Allied invasion of Normandy on 6 June 1944. Most of the 11 panzer divisions that saw action in Normandy initially contained an armored regiment of one battalion of Panzer IVs and another of Panthers, for a total of around 160 tanks, although Waffen-SS panzer divisions were generally larger and better equipped than their Heer counterparts. Regular upgrades to the Panzer IV had helped to maintain its reputation as a formidable opponent. The bocage countryside in Normandy favored defense, and German tanks and anti-tank guns inflicted very heavy casualties on Allied armor during the 