The Second Manchu Invasion refers to the military campaign by the Manchu people in the mid-17th century, specifically from 1644 to 1645. This invasion followed the fall of the Ming Dynasty, as the Manchus sought to expand their territory and consolidate power in China. They successfully captured the capital, Beijing, marking the beginning of the Qing Dynasty. During this period, the Manchus faced resistance from various factions, including remnants of the Ming loyalists. Despite this, the Manchu forces utilized superior military tactics and organization, ultimately establishing their rule over China, which lasted for nearly three centuries.