The Qin Dynasty achieved unification and rose to power through a combination of extensive military campaigns as well as political maneuvering that eventually allowed it to absorb its rival states. It became the first imperial dynasty ruling over a unified China after the end of the Warring States Period in 221 BCE.
The first Emperor of China, Qin Shi Huangdi began his conquest of China from his position as King of Qin. By the time of his ascension, the state of Qin already had a strong military force and capable generals. It followed a legalist philosophy in battle, which encouraged ruthless warfare. This was in sharp contrast with the stance held by other states in China during the Warring States period, which advocated honorable combat.
The Qin began their campaign to conquer their five rival states with the swift conquest of the state of Han in 230 BCE. Conquest of the remaining states quickly followed, and within nine years, the Qin's conquest of China was complete. In 221 BCE, the last remnants of the Zhou dynasty were deposed in Luoyang, and the state of Qi was conquered by the taking of the city of Linzi. However, internal revolts eventually led to the downfall of the Qin Dynasty in 206 BCE.