Napoleon now entered with renewed zest upon the work of perfecting his Continental System, and in so doing he quarrelled with his brother Louis, King of Holland. The young monarch had followed a liberal policy, devoting his time and energy to the interests of his people, and earning their respect if not their love. Napoleon always regarded the land of dykes and wind-mills as scarcely more than a province of France; Louis was determined that his country should be independent. He was no believer in the Emperor’s plan to keep out British goods, so profitable a source of revenue, and as a consequence an extensive business was carried on between Holland and England. Napoleon threatened, Louis temporised, until the former, holding the trump card, finally settled to annex the Kingdom which so openly defied his wishes and commands. Louis was aware that this would probably be the end of the quarrel, for on the 21st September 1809, Napoleon had written a letter to him setting forth his many grievances. He charged the King with favouring Dutchmen who were well disposed towards England, with making speeches containing “nothing but disagreeable allusions to France,” with allowing “the relations between Holland and England to be renewed,” with violating “the laws of the blockade which is the only means of efficaciously injuring this Power,” and so on. “To sum up,” he concluded, “the annexation of Holland to France is what would be most useful to France, to Holland, and to the Continent, because it is what would be most harmful to England. This annexation could be carried out by consent or by force. I have sufficient grievance against Holland to declare war; at the same time I am quite ready to agree to an arrangement which would yield to me the Rhine as a frontier, and by which Holland would emerge to fulfil the conditions stipulated above.”