In 1627, King Injo's hardline policy against the Later Jin dynasty led to war with Joseon Korea. In 1636, after the Later Jin became the Qing dynasty, they defeated Joseon. King Injo was forced to pledge loyalty to the Qing emperor, Hong Taiji, and signed a treaty at Samjeondo, which included sending his sons, Crown Prince Sohyeon and Hyojong, to China as captives. During his exile, Hyojong defended his brother Sohyeon from Qing threats and participated in battles against the Ming loyalists and other groups to protect Sohyeon, who was Joseon's official heir and lacked military experience. Hyojong's interactions with Europeans in China influenced his views on the need for technological and military advancement in Joseon. He harbored resentment against the Qing for their role in the 1636 war and planned northern campaigns against them as revenge.

In 1645, Crown Prince Sohyeon returned to Joseon to succeed Injo and govern the nation. However, conflicts with Injo, particularly over Sohyeon's openness to European culture and views on Qing diplomacy, led to tension. Sohyeon died under mysterious circumstances, and his wife was executed when she sought the truth behind his death. Injo bypassed Sohyeon's son and selected Grand Prince Bong Rim (Hyojong) as his successor. Upon becoming king in 1649, Hyojong initiated military reforms and expansion. He removed corrupt officials like Kim Ja-jeom and summoned supporters of war against the Qing, including Song Si-yeol and Kim Sang-heon. His military efforts included building fortresses along the Yalu River and adopting new technologies, like muskets, with the help of Dutch sailors.

Despite these preparations, Hyojong's planned northern campaigns against the Qing never materialized. The Qing dynasty had grown stronger, assimilating the vast Han army. However, the reformed Joseon military proved effective in 1654 and 1658, aiding the Qing against Russian invasions in battles that demonstrated the stability of the Joseon army. Hyojong also focused on agricultural development and continued reconstruction efforts started by Gwanghaegun. Despite these achievements, he faced immense stress from various internal and external challenges and died at 39 in 1659 from complications related to diabetes and a temporal artery injury. While his northern conquest plans remained unfulfilled, Hyojong is remembered as a dedicated ruler who strove to strengthen and protect Joseon.