Montu was worshipped before the stone pyramids rose, his name appearing in the Pyramid Texts of the Old Kingdom alongside the greatest gods of the solar cult. In those earliest centuries he was not yet a war god but a manifestation of the sun itself, the scorching heat of Ra's rays that burned the earth and withered the crops. The Egyptians called him Montu-Ra, the destructive aspect of the sun god, and they understood that the same force that brought life could also bring death. He was depicted as a falcon-headed man wearing the solar disk and twin plumes upon his head, the plumes distinguishing him from Horus and the other falcon gods, and he carried the khepesh, the curved sword that became the emblem of Egyptian military power. In the Pyramid Texts of Pepi I, around 2300 BCE, the king declares that when Montu is high, he too will be high, and when Montu courses through the sky, the king will course with him, a promise that the pharaoh's soul would follow the celestial falcon to the imperishable stars.

Montu's transformation from solar deity to war god came with the rise of the 11th Dynasty around 2134 BCE, when the rulers of Thebes turned to the ancient falcon god as their protector and patron. Thebes was a provincial city in those days, overshadowed by the northern kingdoms that had ruled Egypt since the collapse of the Old Kingdom, but the Theban kings were ambitious and warlike, and they saw in Montu the perfect symbol of their own aggressive spirit. Mentuhotep II, the pharaoh who would reunite Upper and Lower Egypt after decades of civil war, took a name that meant "Montu is Satisfied," and his successors Mentuhotep III and Mentuhotep IV bore the same divine endorsement. Under their reigns Montu became the supreme god of the state, the deity who opened the way for armies, inspired warriors to glorious deeds, and crushed the enemies of Maat, the goddess of truth and cosmic order. The Egyptian armies marched beneath the standards of the "four Montu," the god in his four primary forms: Montu of Thebes, Montu of Armant, Montu of Medamud, and Montu of El-Tod, each one represented as a falcon-headed warrior trampling enemies beneath his feet and piercing them with a spear.

But Montu's supremacy was brief. When Amenemhat I founded the 12th Dynasty around 1991 BCE, he took a name that meant "Amun is at the Forefront," and the hidden god of Thebes began his meteoric rise to national dominance. Amun merged with Ra to become Amun-Ra, the king of the gods, and Montu was pushed to the margins, reduced from state deity to specialist war god. Yet he did not disappear. Instead he became the aggressive aspect of kingship, the divine fury that the pharaoh called upon when diplomacy failed and the sword was needed. In the New Kingdom, the greatest warrior kings of Egypt claimed Montu as their own. Thutmose III, the pharaoh who conquered an empire stretching from Nubia to Syria, was described in inscriptions as a "Valiant Montu on the Battlefield," and his son Amenhotep II boasted that at the age of eighteen he could shoot arrows through copper targets while driving a war chariot, declaring that he had the strength and skill of Montu himself. Ramesses II, the great builder king of the Nineteenth Dynasty, erected a cult statue of himself as Montu in his Delta capital, calling it "Usermaatre Setepenre, Montu-in-the-Two Lands," a fusion of king and god that declared the pharaoh and the war deity to be one.

Montu was not only a falcon. He was also a bull, and this aspect of his nature gave rise to one of the most important animal cults in Egypt. At Armant, the ancient city the Greeks called Hermonthis, the Egyptians worshipped the Buchis bull, a white beast with a black snout that was believed to be the living incarnation of Montu. Like the Apis bull of Memphis, the Buchis was chosen by priests according to sacred markings, served by a staff of dozens, and buried with full royal honours when it died. The bull's mother was venerated as the "Isis cow" and interred in the Baqqariyah, a separate catacomb near the Bucheion, the underground burial complex at Armant where the mummified bulls rested in granite sarcophagi. The Buchis was renowned for its ferocity, and scenes of bull fighting from Old Kingdom tombs show the animal in its most aggressive form, a living weapon that embodied the war god's unstoppable rage. In the Late Period, from the seventh to the fourth centuries BCE, Montu was even depicted with a bull's head rather than a falcon's, a visual declaration that the god of war was as much beast as bird.

The four cult centres of Montu formed a sacred network across the Theban nome that the Egyptians called the Theban Palladium, a web of temples and festivals that kept the war god's power alive even as Amun dominated the skyline. At Karnak, north of the great temple of Amun-Ra, stood the precinct of Montu, a complex dwarfed by its neighbour but still magnificent, expanded by Taharqa of the 25th Dynasty and enclosed by Nectanebo I with a stone wall. At Medamud, north of Karnak, the temple celebrated Montu as "Lord of Thebes, the bull who dwells in Medamud," and inscriptions describe staged bull fights held in a special arena as part of the god's festivals. At El-Tod, across the river from Armant, the god was called "Montu, the bull who descends from Tod," and at Armant itself he was "Montu, Lord of Thebes, the bull of Armant who comes forth from Tod," a title that traced his journey between the two sacred sites. The 18th Dynasty pharaohs built falcon ships in his honour, models of which were found in the tomb of Amenhotep II, each one bearing the name of a different Montu and serving as both warship and divine barque.

When the Greeks came to Egypt they identified Montu with Ares, their own god of war, though some also connected him with Apollo because of his solar radiance. The Ptolemies and Romans continued to honour him at his Theban temples, and the cult of the Buchis bull persisted at Armant until the Christian era. In the end, Montu remains the eternal warrior, the falcon whose plumes never stopped shaking over the battlefields of Egypt, the bull whose rage could not be tamed, and the god who proved that even when a deity loses his throne, he can still win every war.