Original sentence: The initial production Panthers had a face-hardened glacis plate (the main front hull armor piece), but as  armor-piercing capped rounds become the standard in all armies (thus defeating the benefits of face-hardening, which caused uncapped rounds to shatter), this requirement was deleted on March 30, 1943
Edited sentence: The initial production Panthers had a face-hardened glacis plate (the main front hull armor piece), but as armor-piercing capped rounds become the standard in all armies (thus defeating the benefits of face-hardening, which caused uncapped rounds to shatter), this requirement was deleted on March 30, 1943