Jeong Yeo-rip's "rebellion" while the Southerners were largely Yi Hwang's disciples and less affected. The Southerners, led by Yu Seong-ryong, were initially in power after Japanese Invasion in 1592, and maintained the policy of coexistence with Northerners and Westerners until its effort to reach peace agreement with Japan failed. The Northerners, now in power, split again over the proper successor to Seonjo, who had no legitimate son. Greater Northern faction supported Gwanghaegun while Lesser Northern faction supported another prince. During Gwanghaegun's reign, Greater Northern faction split further and persecuted other factions until Southerners and Westerners joined their forces in a coup d'état that deposed Gwanghaegun and placed Injo on the throne. With the Westerners back in power, Joseon politics entered more stable stage in which they competed with Southerners in relatively peaceful coexistence for about 100 years. But under Hyojong's reign, the Western faction was becoming more powerful. Sukjong's reign In the early years of Sukjong's reign, the Southern faction and Western faction clashed over Royal Funeral Dispute, a seemingly minor issue regarding mourning period for Queen Insun. The Southern faction claimed that mourning period should last one year while Western faction argued for a nine-month mourning period. A one-year mourning period meant that Hyojong was considered the eldest son while 9-month period would suggest that Hyojong was considered not the eldest son, following the rules that governed the yangban class. In other words, Western faction viewed the royal family as the first of yangban class rather than a separate class for which different rules applied. The two factions were also in conflict over issue of fighting Qing Dynasty, which was considered barbarian country (as opposed to Ming Dynasty) that threatened Joseon's national security. Southern faction, led by Huh Jeok and Yoon Hyu, supported war against Qing while Western faction wanted to focus first on improving domestic conditions. Under Sukjong's reign the factional fight became more intense and deadly since Sukjong frequently replaced faction in power with another one to strengthen the royal authority. With each change of government, which was called hwanguk (환국 換局), literally turn of the state, the losing faction was completely driven out of politics with executions and exiles. Westerners vs. Southerners Sukjong at first sided with the Southern faction, but in 1680, Huh Jeok was accused of treason by Western faction, which led to execution of Huh Jeok and Yoon Hyu and purge of Southern