Chess opening are so complex and theoretical that amateur players will have trouble understanding them. An example is the Perenyi Attack of the Sicilian Defense (see diagram) which yields an immensely complicated and tactical position that even strong players have difficulty handling, and that is beyond the comprehension of most amateurs. Major changes in the rules of chess in the late fifteenth century increased the speed of the game, consequently emphasizing the importance of opening study. Thus, early chess books, such as the 1497 text of Luis Ramirez de Lucena, present opening analysis, as does Pedro Damiano (1512), and Ruy López de
War and Peace (game) commanding general's box, reducing clutter on the map), while the alliance chart, force pools, and prisoners are on the campaign game card. Player sides are: France (blue), Spain (yellow), Britain (red), Austria (white), Prussia (gray), and Russia (green). The markers for Fortresses, entrenchments and demoralization are black. Tactical matrix markers (see below) are white. Strength points are also rated for what the game calls "morale" (a proxy for troop quality). Militia, landwehr, partisans and cossacks rate "0". Regular infantry (yellow lettering for minor countries, or black for Prussian, Austrian or Spanish regulars) rate "1". British, Russian and French infantry (white