Panzer I it still performed much useful service against entrenched infantry and other "soft" targets, which were unable to respond even against thin armor, and who were highly vulnerable to machine gun fire. The small, vulnerable light tank, along with its somewhat more powerful successor the Panzer II, would soon be surpassed as a front-line armoured combat vehicle by more powerful German tanks, such as the Panzer III, and later the Panzer IV, Panzer V, and Panzer VI; nevertheless, the Panzer I's contribution to the early victories of Nazi Germany during World War II was significant. Later in that war the turrets
Mk 2 grenade replaced by the silent and more reliable 4 to 5 second delay M204 or M204A1 fuse. Due to the large number of grenades already issued, few grenades with the new fuses were used in combat during WWII. The original Mk 2 grenade had a threaded plug in its base, which covered the opening used to place the explosive filling, either of TNT, of Trojan explosive (a mixture of 40% nitrostarch, ammonium nitrate, and sodium nitrate), of a 50/50 amatol/nitrostarch mixture, or of Grenite (a mixture of 95% nitrostarch and binders). Some early Mk 2 grenades were filled with of smokeless