Nations formed alliance with other nations to become stronger either by contributing lots of nations together and to attack other nations.
An alliance of nations is called a coalition.
The defensive alliance of communist nations was called the Warsaw Pact.
The two nations formed an alliance to defend each other in case of attack.
An alliance.
You are probably thinking of the League of Nations (an organization which has been replaced by the United Nations) but in any event, if nations league together, they form an alliance, or a cooperative group.
Allies
Other nations in Europe formed alliance with Spain
They formed an alliance with the First Nations people so they could trick them into selling them their land for a low amount of money.
Alliance for Europe of the Nations was created on 2002-06-25.
The alliance system was created by Otto von Bismark, and later formed the alliances between the Central Powers and the Great Powers in WWI. Technically, it hasn't ended. The "League of Nations" was created by the Americans before WWII (though America didn't join it), and was another form of alliance. After WWII, there is now something called the "United Nations" which is also a form of alliance. -Sangel99
NATO
The alliance was between three monarchies, Germany, Austria-Hungary and Italy.