After the Roman Empire there wasn't any gunpowder in the west but as a result of the crusades, gun powder was introduced to the west increasing the development of their combat immensely. Crusades were fierce and brutal battles brought upon by the pope to seize Jerusalem (which was recently invaded by the Turks) as the Turks stopped Christians enter Jerusalem, which meant that they couldn't go on pilgrimages there.
After the period of the crusades, after WWI and WWII there was a Cold War. Afterwards Hiroshima and Nagasaki were bombed the USA was declared the only world nuclear power but four years later the Soviet Union had created their own Atom bomb. That is when the USA had a thought of building the more powerful H-bomb or Hydrogen bomb and they soon developed it in 1952 when they had finished it although, soon, the USSR had created their own just three years later. This made a great impact creating a bomb that can easily blow up a whole city; with such strong power, and, if the owner doesn't take careful consideration about how to use such a monstrous weapon, it could end terribly or be used for the wrong purposes.
The cold war also saw a revelation in tanks as the most developed main battle tanks with harder shelters and a greater range in shooting power were invented. These tanks have a great upper body structure that is incredibly hard to penetrate. Furthermore the missiles are much more powerful and are longer from about 10mm-18mm in length. Therefore a genius idea that had been soon developed was the Swimming Polish PT-76s which could be parachuted and attack then left to swim away easily without needing to take the peril to come inland and may be attacked. It would shoot at a very long range and soon swim away so the attack back, couldn't be delivered. Shortly infra red guided missile launchers onto the tanks were produced; they had great accuracy and nearly never missed, which made it the ultimate massacring machine.
