The rapid growth of seventeenth-century science is said to have been facilitated from four main outside channels: the arts, medicine, economic life and war, each of them influencing, to some extent, the important scientific achievements of the latter half of the century. The bitter campaigns of the English Civil War stimulated a rough and ready empiricism, as military necessity brought forth increasing advances in engineering, navigation, cartography, medicine and surgery. And the impetus to inventive genius provided by long experience in the art of war is well exemplified in the career of the Royalist Commander, Prince Rupert of the Rhine. After nearly forty years of waging war on land and sea, Prince Rupert, German-English nephew of Charles I, spent his retirement in busy experiment; and many of his inventions, though based on his knowledge of weapons, were later adapted for peaceful purposes.