In 1806 a rupture between Sweden and Prussia was prevented only by Napoleon's assault upon the latter power. After Jena Napoleon attempted to win over Sweden, but Gustav rejected every overture. The result was the total loss of Swedish Pomerania, and the Swedish army was saved from destruction only by the ingenuity of Johan Christopher Toll. At Tilsit the emperor Alexander I of Russia had undertaken to compel "Russia's geographical enemy," as Napoleon designated Sweden, to accede to the newly established "Continental Russian System". Gustav IV rejected all the proposals of Alexander to close the Baltic against the English, but he took no measures to defend Finland against Russia. On February 21, 1808, a Russian army crossed the Finnish border. On April 2 the king ordered a general levy of 30,000 men.