World War II, or the Second World War, was a global military conflict. It began as the joining of what had initially been two separate conflicts, with the first beginning in Asia in 1937 (the Second Sino-Japanese War) and the other beginning in Europe in 1939 (the German and Soviet invasion of Poland).
The war split the majority of the world's nations into two opposing military alliances: the Allies and the Axis. It involved the mobilization of over 100 million military personnel, making it the most widespread war in history, and placed the participants in a state of "total war", which erased the distinction between civil and military resources and resulted in the complete activation of a nation's economic, industrial, and scientific capabilities for the purposes of the war effort. Over 70 million people, the majority of them civilians, were killed, making it the deadliest conflict in human history.
Blitzkrieg is a popular name for an offensiveoperational-levelmilitary doctrine which involves an initial bombardment followed by the employment of motorized mobile forces attacking with speed and surprise to prevent an enemy from implementing a coherent defense. The founding principles of these types of operations were developed in the 20th century by various nations, and adapted in the years after World War I, largely by the GermanWehrmacht, to incorporate modern weapons and vehicles as a method to help avoid the stalemate of trench warfare and linear warfare in future conflicts. The first practical implementations of these concepts coupled with modern technology were instituted by the Wehrmacht in the opening theatres of World War II.The strategy was particularly effective to Germany in the invasions of Western Europe and initial operations in the Soviet Union. These operations were dependent on surprise penetrations, general enemy unpreparedness and an inability to react swiftly enough to German offensive operations.
A battleship is a large, heavily armoredwarship with a main battery consisting of the largest calibre of guns. Battleships are larger, better armed, and better armored than cruisers and destroyers.Battleship design continually evolved to incorporate and adapt technological advances to maintain an edge. The word battleship was coined around 1794 and is a shortened form of line-of-battle ship, the dominant wooden sailing warship during the Age of Sail. The term came into formal use in the late 1880s to describe a type of ironclad warship, now referred to as pre-dreadnought battleships. In 1906 the launching of HMS Dreadnought heralded a revolution in battleship design, and battleships constructed subsequently were referred to as dreadnoughts. Battleships were a potent symbol of naval dominance and national might, and for decades the battleship was a major factor in both diplomacy and military strategy. The global arms race in battleship construction in the early 20th century was one of the causes of World War I, which saw a clash of huge battle fleets at the Battle of Jutland. The Naval Treaties of the 1920s and 1930s limited the number of battleships but did not end the evolution of design. Both the Allies and the Axis Powers deployed battleships of old construction and new during World War II.