Quadruple Alliance, a joining together of four nations for a common political or military purpose. Quadruple alliances have included:

1718. Great Britain, France, Holland, and Austria joined to force Spain to abide by the Peace of Utrecht.

1815. Great Britain, Austria, Prussia, and Russia, who had been allies in the defeat of Napoleon, joined to prevent violations of the peace settlement. It is to this alliance that the term Quadruple Alliance most commonly refers.

1834. Great Britain and France allied with the ruling queens of Spain and Portugal to suppress rebel princes in the latter two countries.