130 DUTCH AND ENGLISH ON THE HUDSON this, we can easily understand why the governor of each colony, though instructed to seize and hold every foot of land which could be occupied, was « advised not to antagonize the other friendly nations and thus weaken the alliance against the common enemy. As the power of Spain de- clined, however, and the estimate of the value of the American colonies increased, the friction in the New World became more acute and the instructions from the home governments grew imperative. Affairs then came to an open rupture between New Netherland and New Sweden. In 1651 Gov- ernor Stuyvesant inaugurated a more aggressive policy against the Swedes by building Fort Casimir near what is now New Castle, Delaware, not far from the Swedish fort. Three years later Fort Casimir fell into the hands of the Swedes. The Dutch Government now commanded Stuyvesant to drive the Swedes from the river or compel their submission. As a result the Director and his fleet sailed into the Delaware in September, 1655, and captured one fort after another, till Rysing, the last of the Swedish governors, was completely defeated. Though the colonists were promised security in possession of their lands, the power of