Another gigantic task worthy of the genius of Polhem was the construction of a navigable route from the North Sea across the great inland seas of Sweden to the Baltic, but he was not allowed to finish it. Charles XII. intrusted the work to Polhem, who was to have it ready in five years. In 1718, Polhem commenced by forming an immense sluice, by means of explosions in the rock at Trollhetta. The great waterfalls of said place were to be avoided and the work of completing the sluice was begun, when it was all destroyed by unknown enemies, who dropped beams and planks in the river above, which carried away the dam. The death of King Charles and the impoverished condition of the country made it impossible to continue the work on the great canal system, which had to wait for more than a century for its ultimate completion. With the death of Charles XII. the era of ambitious enterprises came to an end; but Polhem was employed in various works of mechanic improvements in the interest of agriculture, industry and manufactures. Czar Peter of Russia, King George I. of England, and several other monarchs made brilliant offers in order to win Polhem for their countries. He executed several works and inventions abroad, but loved his own country too much to leave it. Polhem exerted a great influence in the interest of his science, both by instruction and by the publication of technical works. Active to the last, he died in 1751. Polhem was a man of a harmonious endowment, amiable and dignified, and preserved his plain mode of living throughout his brilliant career.
Gœrtz led with superior skill the negotiations for peace, while the impoverished country suffered untold miseries as a consequence of his unscrupulous financial schemes. He tried to benefit by the sudden but lasting enmity between Czar Peter and George I., desiring to gain the support of either against the other. The deliberations were held in the archipelago of Aland, with Gœrtz as the representative of the Swedish government. Czar Peter wanted to keep Ingermanland, Esthonia and Livonia, but was ready to cede Finland, which country he occupied, and to assist King Charles with troops in an attack on Denmark. Norway was to be the compensation for the lost Baltic provinces, and the attack on Denmark was to be made from Germany. Charles XII. had no confidence in the czar as an ally and had commenced the conquest of Norway directly and without his aid. No decision was reached in the negotiations with England.