The Knights' Revolt (27 August 15226 May 1523) was a short-lived revolt by several German Protestant, imperial knights, led by Franz von Sickingen, against Charles V, Holy Roman Emperor. It has been called the Poor Barons' Rebellion as it inspired the bloody German Peasants' War of 1524–1526. Background In the late Middle Ages, the imperial knights were in a period of constant decline. The encroachment of urban-dominated trade and industry on traditional agriculture, combined with rising interest rates and declining land values, harmed the knights financially, while the increasingly wealthy cities of the Holy Roman Empire had become powerful enough to resist attacks. The growing power of the higher nobility, or the princes, helped by the introduction of Roman law which was sweeping away previous Common law, hurt the knights politically. On top of this, their importance in combat was declining with the advance of military technology and tactics. Mercenary Landsknechts were now the staple of warfare, and the importance of personal ability and bravery in warfare was much reduced. The effectiveness of the arquebus was apparent by the Battle of Cerignola of 1503, which is the earliest-recorded military conflict where arquebuses played a decisive role in the outcome of battle. The heavy arquebus known as the musket appeared in Europe by 1521. The knights refused to co-operate with either the higher nobility to gain power from the cities, or with the cities against the princes. Even had the knights attempted to work with the cities or the higher nobility to bring about reform it is extremely unlikely that the higher nobility would have responded favourably. Conditions in Germany were not like conditions in England. In England, the War of the Roses (1455–1485) that brought Henry VII to the throne had spelled the end of the feudal aristocracy. Prior to the reign of Henry VII the feudal aristocracy had free hand in ruling England. On the throne, Henry VII sought to strengthen and centralize his government. To do that he needed funds. When his predecessors on the English throne had attempted to raise additional funds, they sought to obtain additional lands for the crown. Under the feudal system, more land would result in more income. However, Henry VII realized that a more efficient way of raising money for his government was to tax the income of the rising class of merchants—especially those in the trade in wool and woolen cloth.