Which god was the falcon-headed war god of Thebes?

Montu was the falcon-headed war god especially associated with Thebes and Upper Egypt.

Montu began as a solar deity connected with the scorching power of the sun, but that destructive energy developed into a warrior identity. Egyptians imagined him as the divine force behind the pharaoh's courage, conquest, and victory. He was usually shown as a man with a falcon's head, a solar disk, uraeus cobra, and tall plumes. In later periods he could also appear with a bull's head, reflecting the animal's strength and aggression.

Montu was worshipped at several important centers, including Thebes, Armant, Medamud, and El-Tod. The Theban form, Montu of Thebes, was one of several local manifestations of the god. His cult became particularly prominent during the Eleventh Dynasty, when Theban rulers reunified Egypt after the First Intermediate Period and adopted him as a powerful dynastic protector.

Montu is sometimes confused with Horus because both can be falcon-headed and connected with kingship. Their roles differ: Horus was primarily a sky and kingship deity, while Montu was specifically linked with warfare and martial victory. Thebes later became more famous for Amun, but Montu remained an important regional war god.