Introduction The twentieth century played a big part in the mechanization of the battlefield. In World War I, countries introduced the machine gun, a rapid fire gun which could destroy the hordes of enemies that would rush the trench. Because of this, the much of World War I was a stalemate, or tie. Then in 1916, the British introduced the Landship. A giant steel beast that was impenetrable to enemy fire. This would allow the allies to advance on enemy trenches without harm. Located on the side of the Landship were sponsons. These sponsons had two 6-pounder guns that could decimate enemy infantry. Little did the world know, it was the beginning of steel warfare.  Large scale tank battles happened often in World War Two. With newer technology and better weapons, tanks ruled the battlefield, especially the mighty German Panzers. These battles would be commenced on large, open fields and tank crews would have to use their weapons to fire upon enemies that were hundreds of meters away with deadly accuracy. The Allies lacked in tank engineering in World War II. They simply could not penetrate the Germans' tough, thick armor. Allies had to rely on overwhelming the enemy. The Germans were opposite. They had far fewer tanks, but the most superior cannons of the war, capable of penetrating hundreds of millimeters of armor our to almost a kilometer. Why is it that certain guns can penetrate more and do more damage? Energy and velocity is the answer. The more energy behind the shell when it leaves the barrel and the speed at which it leaves at it very critical to winning in a tank battle. Different types of rounds were used after the war. In World War II, APBC (Armor Piercing Ballistic Capped) shells were the most common. They were fast, accurate and could hold a massive amount of explosives. After the war, newer technology allowed the use of HEAT-FS (High Explosive Anti Tank Fin Stabilized) shells. These would allow a large amount of penetration at massive distances. The most commonly used rounds today are APFSDS (Armor Piercing Fin Stabilized Discarding Sabot). This is a pure kinetic energy round.