WW1 was a European conflict. It started with the assassination of Franz Ferdinand, which the Black Hand had organized and carried out. This war was mostly fought with trench warfare, a slow and agonizing way of fighting. It took years to gain land, and usually little was gained anyway. These battles introduced new weapons, including fighter planes, advanced bombers, and new gas weaponry. This also introduced the first tanks, the most famous being the Mark 4, a slow British tank that had 2 main guns or 2 machine guns on either side.
WW2 is tanks at their finest. From the invasion of Poland to the landings at Omaha, the tank could be seen everywhere. It all started with Adolf Hitler declaring war on Poland, along with some other things beforehand. Because Germany attacked Poland, Britian and France teamed up against them. Germany swept through France, but met fierce resistance from the Brits, with many bombing raids happening but Britian struggled through, and came out standing. On the other side of the world, Japan was destroying China and the Korean penensula. Then Japan bombed America, dragging them into the war. Germany made the mistake of declaring war on America, which led to their demise. The Germans also attacked Russia, but Russia fought back, after losing tons of land, and began their push on Berlin. Russia produced tons of tanks, and Germany made better tanks, but less. Russia overpowered them and swept into Berlin, where Hitler commited suicide. The Americans had landed on Normandy, which was a success, which led to the liberation of France. Japan began getting pushed back, due to the Americans and their brutal island hopping campaign, which got almost all the way to Japan before they got hit with 2 A-bombs. This marked the end of the war.
The Winter War began on the 30th of November, 1939, three months after the outbreak of World War 2. The war resulted in the expulsion of the Soviet Union from the League of Nations. The Winter War begun as a result of Soviet demands on Finnish Karelia and the regions of Petsamo and Salla. In turn, the Finnish would be compensated in other lands. These demands were much too much for Finland because it would mean giving up their defenses along the Soviet border known as the Mannerheim line.
The war began with the Soviets being pushed back by the Finns.
The Finnish losses were heavy, having lost about 9% of her territory to the dreaded Soviets. The Finns lost access to the Arctic ocean (not too terrible, what's the point of a frozen over port?) They lost Salla, which also wasn't as big of a deal, only really a border region. The worst losses were the losses of the Finnish gulf islands and Porkkala, bringing Soviet warships ever so close to the capital of Helsinki. The most notable loss was southern Karelia, which the Soviets left unattended and let Vyborg and other cities rot. Finnish Karelians were expelled and replaced with Russians. Communism began spreading into Finland after this war as the terms of the Moscow Peace Treaty did mention that Finland had to lift the ban on communist parties.
The initial plans for Finland by the Russians were to have the Finns cede a rock in the north, smaller sections of southern Karelia, Porkkala, and a lot of islands near their capital. This was unacceptable. The lands demanded would've annexed the Mannerheim line, which would've made Finland a much easier target for future invasion. The islands were too much of a security threat for Finland to agree to. However, the Soviets did agree to pass over land which was previously ceded by Finland to the Soviet Union in the Treaty of Tartu, essentially reversing it. This would've made Finland a puppet state to the Soviets, as it would've meant that the Finnish government had caved. They did not. Finland did offer a different border, which the Soviets did not accept. At this point, the Soviet intentions were clear. They did not want the Finns to be able to defend themselves properly.
The Cold War wasn't necessarily a war - just a bunch of proxy wars to determine what was better, communism (U.S.S.R.), and capitalism (NATO). These nations would fund military groups in areas such as Korea and Vietnam. These were usually brutal campaigns, with many being lost. Vietnam was the most brutal, with Vietnamese soldiers hiding in areas to surprise the inexperienced U.S. soldiers. Korea had its fair share of brutal conflict, with the North Koreans rushing into the south to almost destroy them, but the South came back and almost took over the entire north end. China was involved as well, as they joined later on because they felt that America might go after them afterwards. Tanks were used a lot by the North, so they caused havoc on the South at the start, with the South's anti-tank guns not being able to penetrate the tanks. T-34-85s made a large appearance with the North and Shermans and other American WW2 tanks in the South.
The Persian Gulf, otherwise known as the war on terrorism, contained the "last" major tank battle. It consisted of Bradleys and Abrams, and they took out many enemy tanks. This war was a very major war, with a message being sent from the U.S. that they could easily wipe out their enemies without taking many loses. They killed enough terrorists that they almost entirely dissolved the terrorist group ISIS.
This war is a weird one. Russia is using trench tactics, which were used in WW1, and some pretty old tanks made a debut in Ukraine. The Panzer III was seen by Ukrainian soldiers, and subsequently, shot. It confused the Ukrainians as to why the Russians were using Nazi technology because it was both old and from the opposite side the Russians were on. Tanks are being used by both sides, with the Russians just sending them full speed at Ukrainian drones and anti-tank weaponry. Ukraine got its tanks from America, Russia, Germany, Britain, and France. Russia has been their biggest tank donor throughout the war, even thought it is done non-willingly.