allied
v.v. to join together with another person, group, or country to support each other. You do this when you have a common goal or a shared enemy.
v. to join or unite for a specific purpose, typically through a formal agreement or treaty. Often used in the past participle form to describe political or military cooperation.
The two small companies allied to compete with the larger corporation.
Several local environmental groups allied to protest the construction of the new highway through the forest.
During the conflict, several smaller city-states allied with the empire to secure their borders against the encroaching northern tribes.
The verb is often used with the preposition 'with'. It can be used reflexively ('allied themselves with') or intransitively.
They allied to the neighboring countryThey allied with the neighboring countryThe verb 'ally' typically takes the preposition 'with' to indicate the partner in the alliance.