Shipbuilding received a new impetus after 1611. The Swedish navy and merchant marine, which had almost disappeared since the days of the great Vasa, began to assume new importance, due to the wars and increased commerce. Ships were built in the native harbors, while others were bought in Holland. Officers for the vessels and carpenters for the ship-yards were hired abroad, largely from Holland. The results were soon apparent. Stockholm, which in 1611 was without a single ship (if the statement in the histories be correct) possessed 49 vessels in 1651. In the same year Gothenburg had 18, which three years later had increased to 147, while other staple towns owned 1,000 ships. Shipbuilding tended to develop other industries, as the Swedish statesmen and leaders of industry tried to provide the necessary ship materials at home without going abroad for them. Rope-walks were operated at Stockholm, at Västervik and other places; sailcloth was manufactured at Stockholm and was also bought in large quantities from the peasants of northern Sweden, who were skilled in weaving; anchors, nails and iron articles required for the ships and shipbuilding were either made in Stockholm at the factories of the government or bought from private persons in the kingdom; masts were cut in the forests of northern Sweden and planks, boards and the like were obtained from the saw-mills in the various provinces. Agriculture was, as it is and always has been, the most important industry of the nation. Large quantities of grain were exported, except in years of famine and failure of crops, and, between the years 1637–1642, 2,400,000 bushels were sent to foreign markets. The government also endeavored to improve farming and cattle raising. German and Dutch cultivators were invited into the country to teach the Swedes better methods of tilling the soil, and new species of grain and new breeds of cattle were introduced. German and Dutch sheep were imported, which the peasants were compelled to exchange for their own. Dutchmen skilled in butter and cheese making were induced to settle near Gothenburg and other places, from whom the Swedish peasants learnt new and improved methods. Despite all endeavors, however, the agriculture of Sweden and Finland made slight progress during the period. The continual conscriptions removed large numbers of the farming class from the country and hundreds of farms were left untilled on account of the wars. To remedy this state of affairs the government granted freedom from taxes and other concessions for a period to those who settled on deserted homesteads; but even “such dispensations often went begging” and hundreds of once fertile fields lay for years uncultivated and covered with weeds.