Triple alliance/ Central powers

The triple alliance was a military alliance formed in 1882 between Austria-Hungary, Germany and Italy. This alliance was formed to ensure that if one of the countries were attacked the other countries would back them up. The formation of this alliance alerted other countries and caused the triple entente to form, an alliance between Russia, franc and Britain this alliance was similar to the triple alliance. The formation of these alliances along with Militarism, nationalism, imperialism and the assassination of Archduke Franz Ferdinand sparked WW1. France and Italy came to the agreement that in the case that one of the powers attacked the other, France or Italy would remain neutral with eachother. When Austria-Hungary attacked the triple entente countries, Italy refused to join because the would not participate in an offensive alliance because the triple alliance was designed to be a defensive alliance.  Later on Italy switched sides, to the triple entente, this changed the original formation of the alliance making it so they were no longer alliances consisting of only 3 countries and the triple entente was referred to as the allied powers and the triple alliance was referred to as the central powers from then on. The Ottoman Empire and Bulgaria eventually joined the central powers, many other countries including the US joined the Allied powers. Eventually the Allied powers won WW1.

http://www.britannica.com/EBchecked/topic/605722/Triple-Alliance

http://en.wikipedia.org/wiki/Triple_Alliance_(1882)