The whole idea of naval warfare in those days was defense of your own commerce and attack upon your enemy’s; and at that time any one you met under another flag was likely to be your “enemy” if either party promised spoils worth a fight. Hence not only did privateering flourish,—often degenerating into piracy,—not only did all merchant vessels go heavily armed, but the royal ships were intended principally for convoying or guarding merchantmen. This theory, which was only a part of the generally unsettled condition of that formative period, kept up a continual state of fighting on the sea, even between peoples nominally at peace, and of course led again and again to open wars. These were almost always popular, especially among the bold sailors but poor traders of England, on account of the chances for prizes and plunder that often more than repaid the expenses and losses of the conflict; thus the war with the Dutch in 1652-54, in which William Penn was a captain, brought in more than _£_6,000,000 worth of captures—more than the financial cost of the war. At this time—the first half of the sixteenth century—Holland was the leading commercial nation of the world. Not only had her merchants large interests of their own in both the East and West Indies, very extensive fisheries in northern waters, and trading stations in the African and American coasts, but a large part of the commerce of other nations was conducted in Dutch ships, including much of England itself. It was the unrighteous but determined effort to break this up by any and every means that brought on the second war with Holland, one incident of which was the capture of New Amsterdam (New York); for fleets no longer stayed close at home, acting mainly as defenders of coasts, as in the previous century, but now cruised and fought on the high seas, as the Spanish had learned in many a hard struggle to protect their trading and treasure-ships homeward bound. [Illustration: ATTACKING SPANISH GALLEONS OFF THE AZORES.] [Illustration: DRAWN BY WARREN SHEPPARD. SPANISH AND FRENCH SHIPS OF THE LINE TAKING POSITION FOR THE BATTLE OF TRAFALGAR.]