May 1: Warsaw Treaty on Friendship, Cooperation and Mutual Assistance signed (Warsaw Treaty Organization) (effective June 6).

May 5: West Germany becomes a sovereign country recognized by important Western foreign countries, such as France, the United Kingdom, Canada, and the United States.

May 6: WEU charter effective.

May 9: West Germany joins the North Atlantic Treaty Organization (NATO).

May 11: Japanese National Railways' ferry Shiun Maru sinks after collision with sister ship Uko Maru in thick fog off Takamatsu, Shikoku, in the Seto Inland Sea of Japan; 166 passengers (many children) and two crew are killed. This event is influential in plans to construct the Akashi-Kaikyo- Bridge (built 1986-98).

May 12- New York's Third Avenue Elevated runs its last train between Chathem Square in Manhattan and East 149th Street in the Bronx, thus ending elevated train service in Manhattan.

May 14: Eight Communist Bloc countries, including the Soviet Union, sign a mutual defence treaty in Warsaw, Poland, that is called the Warsaw Pact.

May 15: Austrian State Treaty, which restores Austria's national sovereignty, is concluded between the four occupying powers following World War II (the United Kingdom, the United States, the Soviet Union, and France) and Austria, setting it up as a neutral country.

May 25: Joe Brown and George Band are the first to attain the summit of Kanchenjunga in the Himalayas, as part of a British team led by Charles Evans. (source: Wikipedia)