This book refers to the basic factors of warfare, which is time and space, the tactics and strategy of the forces involved, as well as the impact of warfare on the population and society. In particular, the phenomenon of war is under examination in western Greece during the Late Middle Ages, which has been a period of instability in an area politically fragmented. Localities with unstable and variable borders were formed under continuous wars, whereas the international powers of the era aimed at the occupation of lands. War conflicts were dense and they were conducted according to the ethics of the parties involved, which were the Byzantines, the local Epirote forces, the Serbs, the Albanians, the Venetians, and the Ottomans. The role of space was very important as the whole area obtained a specific defensive character with the formation of fortification systems. But time has been also a defining factor of warfare as it had an effect on the conduct and the result of the military operations; the latter were also influenced by the armed forces, and their tactics and strategy. War had a great impact on the population, though it did not cause its reduction. Furthermore, the society of western Greece was adapted to the conditions of war as it is seen by its participation in war conflicts; however, it did not accept the phenomenon of war.