The French campaign against Korea of 1866 is also known as Byeong-in yangyo (Western disturbance of the byeong-in year). It refers to the French invasion of Ganghwa Island in Korea in retaliation for the earlier execution by Korea's Joseon Dynasty of French Catholic priests proselytizing in that country. The encounter, which lasted nearly six weeks, was the first armed encounter between Korea and a Western power. The overall result was a French retreat and a check on its influence in the region. The violent encounter also confirmed Korea in its isolationism for another decade, until Japan forced it to end its isolationism in 1876 through the threat of military force (see Treaty of Ganghwa).