The Treaty of Saint Petersburg was signed on April 11, 1805 by the British Empire and the Russian Empire and created an offensive alliance directed against Napoleon's French Empire. They were joined by Austria (on August 9), Sweden, while France was allied to Spain, to a number of satellite republics. Sweden only joined after Britain granted subsidies which virtually financed the entire Swedish war costs. Sweden armed 10,000 men. This treaty would be one of the main causes of the War of the Third Coalition.