There was no question in which the insanity of the king became more apparent or disastrous than in his foreign policy. An alliance of armed neutrality between Sweden, Russia and Denmark came to naught through the inactivity of Gustavus IV., and he stubbornly refused to accept the repeated offers of Napoleon of an alliance with France in the combat with the powers. Things took a sinister aspect when an intimate alliance was effected between Napoleon and Alexander of Russia, in 1807. Napoleon had lost patience with the lunatic king, and tried to call forth a catastrophe by urging Alexander to capture Finland, which he at first was unwilling to do. The French invaded Swedish Pomerania, and Toll was able to save the little Swedish army of 10,000 only by means of a most skilful diplomacy. Denmark, attacked by England, declared war against Sweden. Gustavus IV. made great preparations, sending Armfelt with one army to the Norwegian frontier and Toll with another to Scania. The regular army counted 100,000 men, and a great force of militia was organized. But through gross incapability of the government the majority of troops were never used, the militia suffering immensely through neglect and hunger.
Czar Alexander at last decided to capture Finland. He called it himself an act of bad faith and treason against a relative and ally, and in a treacherous way he carried on his preparations. The Swedish ambassador was misled as to the object of the latter, and when informed received exaggerated accounts as to the force which was to invade Finland. Gustavus IV. was alarmed and gave the old and incapable field-marshal, Klingspor, appointed to command the army in Finland, directions to save his troops in the best way possible. And so commenced, in February, 1808, the war which after a heroic struggle was to separate the Finns from their Swedish brethren. Not only were the Finnish troops possessed of the noblest patriotic spirit, but they had also courageous and distinguished commanders, who, if duly supported and intrusted with more authority, would probably have been able to ward off the attack. Conspicuous among the latter were C. J. Adlercreutz, born in Finland, the hero of Siikajoki, Lappo and Oravais; G. C. von Dœbeln, the victor of Juutas, and J. A. Sandels, the hero of Pulkkila, Indensalmi and Virta, all three of them veterans from the war of Gustavus III.