of the royal armies at the battles of Crécy in 1346 and Poitiers in 1356, which caused high levels of social unrest across the remaining French territories. Charles V of France attempted to restore French royal authority and prestige through the construction of a new range of castles. The Château de Vincennes, where a new keep was completed under Charles by 1380, was the first example of these palace fortresses. The keep at Vincennes was highly innovative: six stories high, with a chemin de ronde running around the machicolated battlements; the luxuriously appointed building was protected by an enceinte wall that formed a "fortified envelope" around the keep. The Vincennes keep was copied elsewhere across France, particularly as the French kings reconquered territories from the English, encouraging a style that emphasised very tall keeps with prominent machicolations. No allowance for the emerging new gunpowder weapons was made in these keeps, although later in the century gunports were slowly being added, as for example by Charles VI to his keep at Saint-Malo. The French model spread into Iberia in the second half of the century, where the most powerful nobles in Castile built a number of similar tall keeps, such as that at Peñafiel, taking advantage of the weakness of the Castilian Crown during the period. Henry IV of Castile responded in the 15th century by creating a sequence of royal castles with prominent keeps at the Castle of La Mota, Portillo, and Alcázar of Segovia: built to particular proportions, these keeps became known as a key element of the Valladolid school of Spanish castle design. Smaller versions of these keeps were subsequently built by many aspiring new aristocracy in Spain, including many converted Jews, keen to improve their social prestige and position in society. The French model of tall keeps was also echoed in some German castles, such as that at Karlštejn, although the layout and positioning of these towers still followed the existing bergfried model, rather than that in western castles. The 15th and 16th centuries saw a small number of English and occasional Welsh castles develop still grander keeps. The first of these large tower keeps were built in the north of England during the 14th century, at locations such as Warkworth. They were probably partially inspired by designs in France, but they also reflected the improvements in the security along the Scottish border during the period, and