Panzer III addition, to counter enemy anti-tank rifles, starting from 1943, the Ausf. L version began the use of spaced armour sideskirts and screens (known as "Schürzen" in German) around the turret and on the vulnerable hull-sides. However, due to the introduction of the upgunned and more-armoured Panzer IV, the Panzer III was, after the German defeat at the Battle of Kursk in the summer of 1943, relegated to secondary/minor combat roles, such as tank-training, and it was finally replaced as the main German medium tank by the Panzer IV and the Panzer V Panther. The Panzer III's strong, reliable and durable
QF 4-inch naval gun Mk V and W class destroyers of 1917 also mounted the gun. Mk V was superseded by the QF 4 inch Mk XVI as the HA (i.e. anti-aircraft) gun on new warships in the 1930s, but it continued to serve on many ships such as destroyers, light and heavy cruisers in World War II. Early in World War I several guns were supplied by the Navy for evaluation as anti-aircraft guns for the home defence of key installations in Britain. They were mounted on static platforms and proved fairly successful after a fixed round was developed to replace the original separate round,