An Ally
It means the most powerful individual, group or country on your side.
An ally is one who helps you.someone who is on your side,like in ww2 the people who was on our team basicallyallies are people, groups, or states that have joined in an association for mutual benefit or to achieve some common purpose,
Japan was officially on the same side as the Germans although it was a very unlikely alliance. Thailand was Japan's ally in Asia.
Cuba was an ally to the US during World War II. But after the war, Cuba became communist and joined on the side of Russia against US. Cuba and Russia were also launched the nuclear threat on the US and Mexico.
Treaty
germany
France
According to the Oxford English Dictionary, the definition of ally as a verb is:beneficially combine (a resource or commodity) with; (ally oneself with) side with
ALLY
You can call them an ally, supporter, or advocate.
During World War I, no countries actively supported both sides of the conflict at any time; that is, no country switched sides at some point during the war. While Italy began the war as a "paper ally" of the Central Powers, it did not actively contribute military assistance of any kind to their cause. In 1915, it became a combatant on the side of the Triple Alliance.