World War I
1917 : Britain’s King George V changes royal surname

http://www.history.com/tdih.do?action=tdihArticleCategory&id=696

1939: Bismarck launched


On this day, the German navy launches the 823-foot battleship Bismarck at Hamburg. Adolf Hitler hoped that the state of the art Bismarck would herald the rebirth of the German surface battle fleet. However, after the outbreak of war Britain closely guarded ocean routes from Germany to the Atlantic Ocean, and only U-boats moved freely through the war zone. In May 1941, the order was given for the Bismarck to break out into the Atlantic. Once in the safety of the open ocean, the battleship would be almost impossible to track down; all the while wreaking havoc on Allied convoys to Britain.



Learning of its movement, Britain sent almost the entire British home fleet in pursuit. On May 24, the British battle cruiser Hood and battleship Prince of Wales intercepted it near Iceland. In a ferocious battle, the Hood exploded and sank, and all but three of the 1,421 crewmen were killed. The Bismarck escaped, but because it was leaking fuel, it fled for occupied France. On May 26, it was sighted and crippled by British aircraft, and on May 27, three British warships descended on the Bismarck and finished it off. The German death toll was over 2,000.

On June 20:

1963 - The so-called "red telephone" is established between Soviet Union and United States following the Cuban Missile Crisis.
http://en.wikipedia.org/wiki/Red_telephone

June 21 1788:

New Hampshire becomes the ninth and last necessary state to ratify the Constitution of the United States,
thereby making the document the law of the land.

1941: Hitler invades the Soviet Union

The German Army takes the Soviet leader Joseph Stalin by surprise as it begins a massive advance on Moscow.