How did tanks alter the strategy of World War II battles?

Tanks became a war weapon during WWI. The tanks of that war were quite slow but they could be used against enemy fortifications since they were nearly impervious to machine gun fire. Tanks could also be used to drive over barbed wire defenses. The potential of tanks was not realized during this war as infantry tactics were not used in combination with the tank and the equipment was slow and largely unreliable.

Between the wars, tank technology improved enough to make the tank a formidable weapon during WWII. Tanks provided mobile artillery and anti-personnel weapons that could be used to destroy static fortifications, thus making them obsolete. When combined with infantry and air cover, tanks provided additional firepower for Hitler's blitzkrieg. While the tank would be a liability in urban warfare such as Stalingrad, the tank would prove its worth to both sides on the Russian and Polish plains. Engineers also designed amphibious tanks which could be used in the Pacific Theater, thus giving infantry additional fire support when needed.

The tank by itself lacks the versatility to fight in crowded urban environments; however, when combined with infantry and air support, the tank has proven itself to be effective against a conventional army. The United States and Russia have considerable tank arms; most enemies who have success against either of these superpowers resort to unconventional war which is harder to defeat with a tank corps.

Tanks have revolutionized modern warfare by making it a contest of speed and rapid maneuvers. Tanks have been the kings of the battlefield since World War II (1939–1945). Germany's success during its invasions of Poland and France in 1939–40 first demonstrated the efficacy of modern tank warfare.

Tanks emerged as a potent force because of the deadlock during the fighting in World War I (1914–1918). In WWI, armies—especially those fighting in the West—engaged in protracted trench warfare. Machine guns, barbed wire, massed artillery, and the uselessness of cavalry meant that the armies could not maneuver very much. Tanks were first used in combat during the second half of WWI, but they did not have a decisive impact on the course of the war.

After WWI, the US military was reduced in size, and the research and development of tank warfare stalled. German success at using tanks during the first year of WWII convinced American leaders to focus on tank production. The US produced nearly 50,000 Sherman tanks during WWII. Sadly, American tankers who manned the Shermans had little chance against the German Panther and Tiger tanks. Shermans were nicknamed "Ronsons," after the cigarette lighter which "lit up the first time."

France produced some good tanks during WWII, but it did not use them properly. France's strategy in WWII was too defensive as it relied on its Maginot Line. In the end, the Maginot Line was outflanked by German tanks.

The Soviet Union manufactured the magnificent T-34 tank during WWII. Also, it won the largest tank battle in history against the Germans at Kursk in 1943.

Tanks have remained important since WWII ended. For example, Israel has had a great deal of success with its tank units. Israel's enemy, Hezbollah, used effective anti-tank weapons against Israel in their last war in Lebanon, though.

The tank, which was developed after its predecessor, the armored truck, was meant to be able to cover rough terrain due to the trench warfare. Trench warfare involves the digging of trenches to make it hard for the enemy to advance, but with the development of crude versions of the tank the trench defense system became obsolete during the end of the First World War and beginning of the Second World War. Fundamentally the tank was developed and employed to breach the enemy’s defense lines, especially during a stalemate. The tank changed warfare because it had the capacity to withstand bombardment, machine gun fire, and barbed fences. This reduced injuries and fatalities to the soldiers. Tanks were predominantly used to lead and prepare the way for the infantry units and provide cover for assault operations. The tanks developed also helped in carrying surface to air missiles to repel air attacks from the enemy, thus revolutionizing both land and air warfare.

The invention of tanks made defenisve trench networks in the style of WWI obsolete.  It returned mobility to the battlefield and helped to bring about the "blitzkrieg" style of warfare that worked so well for the Germans in the early part of WWII.

Things like barbed wire and machines guns and trenches had turned warfare (from about the time of the US Civil War through WWI) into a process in which the defense had a huge advantage.  Tanks changed that.  They were able to drive over all sorts of terrain, including trenches and they were able to smash barbed wire.  They were able to move quickly, acting as cavalry used to act.

By doing these things, tanks changed battle.  This is one reason why WWII saw no repeat of the trench warfare of WWI.