Western ancient military thought originated in Europe, North Africa and West Asia around 4000 BC. With the emergence of slave countries and social forms, the early western military civilization also came into being. The rise and prosperity of ancient Egypt, ancient Persia, ancient Rome and ancient Greece are largely accompanied by fierce wars, conflicts and endless military contests. When the West entered the feudal era, with the continuous improvement of social productive forces, the continuous development of military technology and the increasing expansion of human activities, foreign wars of some European powers for different purposes became increasingly frequent. In the long history of slave society and feudal society, western countries have gradually formed a relatively rich accumulation and systematic understanding of human armies and wars.

Tribal military democracy was first practiced in ancient Greece. With the continuous improvement of the level of social productive forces, the city-states rise rapidly, and they often have merger wars because of interest disputes. Sparta was one of the most powerful city-states at that time. Strict military management was carried out among all citizens, and citizens were soldiers. The whole society is like a military camp, and military training is an important part of every Spartan's daily life. The Persian War, the Peloponnesian War and other large-scale wars broke out one after another, which brought great shock and influence to Greek society. During the war, Tailhade, Xenophon, Alexander and other famous military generals rationally thought and summarized the war issues, and became the pioneers of western military theory research. Thucydides has realized in the history of the Peloponnesian War that the root of the war is not accidental conflict, but the product of irreconcilable conflicts of interests. Perikles, commander-in-chief of Athens, also pointed out that the war not only safeguarded the interests of the empire, but also safeguarded the interests of each individual. During the Peloponnesian War, Macedonia rose rapidly with military reform, and Alexander the Great invaded Wan Li and established a great empire across Europe, Asia and Africa. During the ten-year campaign, Alexander the Great was recorded in the history of western military thought with his exquisite strategic command, flexible tactical choice and clever use of political and military means.

The earliest imperial period of ancient Rome also belonged to the nature of military democracy. Since then, slave city-states have emerged and aristocratic republics have been established. In the long war, ancient Rome formed a military organization characterized by legions, with strict discipline and clear rewards and punishments. In the increasingly frequent external expansion, a large number of brave generals such as Scipio and Caesar have emerged. The brand-new strategy, tactics, tactics and advanced military technology created by the Punic War, which lasted for a hundred years, pushed the development of ancient western military thought and war practice to a new height and had a far-reaching impact on later generations. The ancient Romans attached great importance to the study of war. Caesar's Battle of Gaul, Frontinus's Strategy, Vegetius's Introduction to the Art of War and other military theoretical works have summarized the purpose, nature, factors affecting the outcome, operational strategies and principles, and the training and management of the army, which have had an extremely important impact on the practice of military struggle at that time.

In the Middle Ages, major European countries introduced various military reform measures to meet the needs of different wars, such as dynastic wars, hegemonic wars and aggressive wars, and to maintain and strengthen their feudal rule. A large number of war practices, such as the Arabian-Byzantine War, the Hundred Years' War between Britain and France, and the Crusades, have brought a large number of military strategists with military command ability and strategic vision to history, and a number of military works represented by War, General and Science of Tactics have emerged, enriching the treasure house of ancient western military thoughts. However, the development of western military thought in this period was influenced, interfered and restricted by religious theology to a certain extent, so the understanding of the nature of war was mostly religious.