After the peace at Traventhal Charles XII. turned his forces against Russia and Poland, where he won victory after victory, until finally, on the 27th of June, 1709, he lost the battle of Pultowa. On account of the dangerous position in which this defeat placed the Swedish king, King Frederick thought the opportunity had come to recover the lost provinces. He renewed his old allegiance with Russia and Poland, and began the Great Northern War (1709-1720). With 16,000 men he invaded Scania and captured several towns; but the Swedish field-marshal, Magnus Stenbock, hastily gathered an army of undisciplined peasants and defeated the Danes at the battle of Helsingborg (1710). In this war also the Danish-Norwegian fleet rendered great service, fighting the Swedish fleet with success in the Baltic and especially in the North Sea. On October 4, 1710, it was attacked by the Swedish fleet in Kjögebugt. The Norwegian, Ivar Hvitfeld (a son of Tonne Hvitfeld, who had distinguished himself at Frederickshald), commanded the ship "Dannebrog," which took fire early in the fight. He might have saved himself by beaching the ship, but there was danger of thus spreading the fire to the rest of the Danish fleet and to the town. He therefore stayed where he was, drew closer to the enemy and fired volley after volley from the forward guns, until the fire reached the powder magazine. The ship was blown up, and he and his five hundred men perished. In the latter part of 1715, Charles XII. returned to Sweden, after an absence of fifteen years, and succeeded in giving new courage to the Swedes, who were exhausted from the hardships of the long war. The winter was very severe, so that the Sound was frozen over, and, in January, 1716, Charles intended to lead his army of 20,000 men across the ice and invade the Danish islands; but, just as he was ready for this exploit, a thaw suddenly set in, so that he could not effect the crossing, and, not having sufficient transports, Charles decided to direct his attacks against Norway. The defences of Norway were in a miserable condition. The trained regiments had been sent south to Denmark, so that the army consisted almost wholly of the National Guards, which were without training, poorly clothed, and without the necessary supplies. The fortresses were short of provisions, arms, and ammunition, and there was no money in the treasury. The commanding general, the old and feeble Barthold von Lützow, had to confine his operations to garrisoning the silver works at Kongsberg and the principal passes. The natural advantages of the country and the patriotism and perseverance of the inhabitants constituted the principal defence.