After the US Congress rejected its Carlisle Commission, Britain responded by taking aggressive action against any nation providing military assistance to the US Congress. It reasoned that violated Parliament's mercantile trade restrictions for its Thirteen Colonies. For Britain, the colonial civil war with Congress that began formally at its 1776 Declaration of Independence, now expanded into a war worldwide, beginning when France declared the Anglo-French War of 1778. By April 1779, Spain joined France to war against Britain in the secret Treaty of Aranjuez. Spain sought to reclaim the portion of its empire that it had lost to Britain at the last peace, including Gibraltar, Minorca, and the Floridas.