In the following year, 1617, Gustavus Adolphus, then about to conduct an expedition into Livonia, sent an envoy to Holland for the purpose of securing the good offices of the States-General for the raising of a loan upon the security of the Swedish copper mines.

The principal contributor was Louis de Geer.

He had, during his visit to Sweden, learnt how great was the wealth of that country in iron ore, and at the same time that the mines were lying idle and undeveloped through lack of capital and skilled workmen.

He used his opportunity therefore to obtain from Gustavus the lease of the rich mining domain of Finspong.
The lease was signed on October 12, 1619, and de Geer at once began operations on the largest scale.

He introduced from Liege a body of expert Walloon iron-workers, built forges and factories, and was in a few years able to supply the Swedish government with all the ordnance and munitions of war that they required, and to export through the port of Norrkoeping large supplies of goods to his warehouses at Amsterdam.
His relations with Gustavus Adolphus soon became intimate.