Which Inca ruler was known for his military campaigns and expansion?

Pachacuti was the Inca ruler known for major military campaigns and imperial expansion.

Pachacuti Inca Yupanqui became the ninth Sapa Inca and is widely credited with transforming the small Cusco kingdom into the core of a powerful empire. His rise followed the Inca victory over the Chanka, a conflict remembered as a decisive turning point. Afterward, he conquered or brought surrounding peoples under Inca control and reorganized the expanding state.

Pachacuti personally led early campaigns near Cusco, while later expeditions were directed by generals and his son, Topa Inca Yupanqui. During his reign, Inca power spread across parts of the southern Andes, the Lake Titicaca region, the central Andes, and territories toward the north. He also strengthened administration, infrastructure, and the imperial capital.

Atahualpa was a later ruler involved in the civil war immediately before the Spanish conquest, while Túpac Yupanqui continued expansion after Pachacuti. Manco Cápac is traditionally regarded as the founding ancestor of the Inca dynasty, not the ruler most associated with imperial military expansion.