The inhabitants of Harlem felt their danger. Bossu, Alva's stadholder for Holland, had formally announced the system hitherto pursued at Mechlin, Zutphen, and Naarden, as the deliberate policy of the government. The King's representative had formally proclaimed the extermination of man, woman; and child in every city which opposed his authority, but the promulgation and practice of such a system had an opposite effect to the one intended. The hearts of the Hollanders were rather steeled to resistance than awed into submission by the fate of Naarden." A fortunate event, too, was accepted as a lucky omen for the coming contest. A little fleet of armed vessels, belonging to Holland, had been frozen up in the neighbourhood of Amsterdam. Don Frederic on his arrival from Naarden, despatched a body of picked men over the ice to attack the imprisoned vessels. The crews had, however, fortified themselves by digging a wide trench around the whole fleet, which thus became from the moment an almost impregnable fortress. Out of this frozen citadel a strong band of well-armed and skilful musketeers sallied forth upon skates as the besieging force advanced. A rapid, brilliant, and slippery skirmish succeeded, in which the Hollanders, so accustomed to such sports, easily vanquished their antagonists, and drove them off the field, with the loss of several hundred left dead upon the ice. "'T was a thing never heard of before to-day," said Alva, "to see a body of arquebusiers thus skirmishing upon a frozen sea." In the course of the next four-and-twenty hours a flood and a rapid thaw released the vessels, which all escaped to Enkhuyzen, while a frost, immediately and strangely succeeding, made pursuit impossible. The Spaniards were astonished at these novel manoeuvres upon the ice. It is amusing to read their elaborate descriptions of the wonderful appendages which had enabled the Hollanders to glide so glibly into battle with a superior force, and so rapidly to glance away, after achieving a signal triumph. Nevertheless, the Spaniards could never be dismayed, and were always apt scholars, even if an enemy were the teacher. Alva immediately ordered seven thousand pairs of skates, and his soldiers soon learned to perform military evolutions with these new accoutrements as audaciously, if not as adroitly, as the Hollanders.