Gustav Adolf was a wise and generous foe.  While he lived he refused to listen to proposals for the partition of Denmark after King Christian’s defeat in Germany.  He knew well that she was a barrier against the ambition of the German princes and that, once she was out of the way, Sweden’s turn would come next.  But when he had fallen on the battle-field of Luetzen, and his generals, following in his footsteps, had achieved fame and lands and the freedom of worship for which he gave his life, the Swedish statesmen lost their heads and dreamed of the erection of a great northern Protestant state by the conquest of Denmark and Norway, to balance the power of the German empire.  Without warning or declaration of war a great army was thrown into the Danish peninsula from the south.  Another advanced from Sweden upon the eastern provinces, and a fleet hired in Holland for Swedish money came through the North Sea to help them over to the Danish islands.  If the two armies met, Denmark was lost.  In Swedish harbors a still bigger fleet was fitting out for the Baltic.

King Christian was well up in the sixties, worn with the tireless activities of a long reign; but once more he proved himself greater than adversity.  When the evil tidings reached him, in the midst of profound peace, the enemy was already within the gates.  The country lay prostrate.  The name of Torstenson, the Swedish general, spread terror wherever it was heard.  In the German campaigns he had been known as the “Swedish Lightning.”  Beset on every side, never had Denmark’s need been greater.  The one man who did not lose his head was her king.  By his personal example he put heart into the people and shamed the cowardly nobles.  He borrowed money wherever he could, sent his own silver to the mint, crowded the work in the navy-yard by night and by day, gathered an army, and hurried with it to the Sounds where the enemy might cross.  When the first ships were ready he sailed around the Skaw to meet the Dutch hirelings.  “I am old and stiff,” he said, “and no good any more to fight on land.  But I can manage the ships.”

And he did.  He met the Dutchmen in the North Sea, in under the Danish coast, and whipped them, almost single-handed, for his own ship Trefoldigheden was for a long while the only one that wind and tide would let come up with them.  That done, he left one of his captains to watch lest they come out from among the islands where their ships of shallower draught had sought refuge, and sailed for Copenhagen.  Everything that could carry sail was ready for him by that time; also the news that the Swedish fleet of forty-six fighting ships under Klas Fleming had sailed for the coast of Holstein to take on board Torstenson’s army.

King Christian lost no time.  He hoisted his flag on Trefoldigheden and made after them with thirty-nine ships, vowing that he would win this fight or die.  At Kolberger Heide, the water outside the Fjord of Kiel, he caught up with them and attacked at once.  The battle that then ensued is the one of which the poet sings and with which the name of Christian IV is forever linked.