Final answer:
Pachacuti was the first Inca emperor to use warfare for the empire's expansion, through conquests in the Ecuadorian lowlands, the rainforests of current-day Bolivia and Peru, and against the Chimor. After Pachacuti, his son Tupac Inca Yupanqui continued the military campaigns.
Step-by-step explanation:
Pachacuti was the first Inca emperor to use warfare for expansion. The significant leap for the Inca Empire began in the mid-fifteenth century under his leadership.
Pachacuti initiated imperial conquests by targeting regions in the Ecuadorian lowlands, the rainforests of what is now Bolivia and Peru, and most notably, against the Chimor to the north of Cusco. His victory over the Chimor marked a notable expansion of the Inca Empire.
Subsequently, Pachacuti's son, Tupac Inca Yupanqui, continued these conquests during his reign, further extending the boundaries of the empire.
Inca soldiers were well-equipped with helmets, cloth armor, shields, and weapons such as clubs, spears, slings, and axes. Their military strategies often relied on overwhelming numbers to intimidate and sometimes to force enemy capitulation. When necessary, they engaged in battles demonstrating great courage and resolve.
The extensive network of highland roads in the empire facilitated swift troop movements, which greatly aided their conquest strategies.
However, the Inca preferred voluntary surrender and would often employ a blend of diplomacy and strategic displays of might to expand their territory. This approach of seeking surrender over outright battle is reminiscent of the methods used by the Aztecs.
The Inca Empire ultimately met its demise in the 1530s with the arrival of European diseases and the Spanish conquest. Despite their achievements in warfare and empire building, the military strength of the Inca was no match for the diseases and the military tactics employed by the Spanish, including those of the conqueror Francisco Pizarro.