SLAVERY 227commoner population and reduce the number of slaves had been frustrated by
the resurgent power of the slaveowners, but only because the country was at
peace and enjoyed the security afforded by the protection of the Ming empire.
When national security was threatened in the middle of the sixteenth century
by sporadic attacks by Jurchen tribesmen along the northern frontier and pirates
off the southern coast, the critical shortage of adult males of good or commoner
status for military service became apparent. In 1554 and T 555 the government
recruited slaves for military duty in the north and manumitted them in reward
for their service, just as the Koryo regime had done in times of crisis. Never-
theless, because of strong opposition from owners who objected to the loss of
their property and officials who opposed any weakening of the social order, the
government had to backtrack and limit manumissions only to slaves who
engaged in combat. The incident showed, however, how the threat of war might
weaken the Korean social system.^79
At the end of the century the Korean people had to suffer through one of the
most destructive periods in their national history. The invasions of Hideyoshi
(the Imjin War) and the occupation of part of the peninsula by Japanese forces
lasted for almost seven years, from 1592 to 1598. The war had barely ended
before a new enemy appeared on the scene. The Manchus under Nurhaci were
gaining power and challenging the declining Ming, and the Koreans were caught
between the two rivals. The conflict resulted in two invasions by the Manchus,
in 1627 and 1637. Bitter rancor over the invasions and the severity of Manchu
tribute demands kept anti-Manchu feeling at a high pitch, and in the 1650S under
King Hyojong there was even talk of an armed expedition to Manchuria in
reprisal. The half century of war and tension maintained pressure on the gov-
ernment to keep the military ranks filled.
Almost immediately after King Sonja fled the capital in the spring of 1592 to
avoid capture by Japanese forces, slaves and refugees attacked the Slave Agency
(Changyew6n) and Ministry of Punishment and put all the slave registers to the
torch.^80 In the long run, however, the pressure on the government for expansion
of the male population available for military service and taxes was more sig-
nificant in weakening the restraints of the social system than isolated acts of
destruction.
During the wars against Hideyoshi a number of measures were adopted that
allowed the manumission of slaves in return for military service or specific acts
of heroism or prowess. Manumission and appointment to office continued to be
used well into the eighteenth century to reward the achievements of slave sol-
diers in the repression of rebellion or defense against raiders along the frontier,
and another schedule of rewards was even drawn up in [646.
In 1593 King S6njo also decided to allow private as well as official slaves to
stand for the military examinations, and if they passed, to be manumitted and
enrolled in the royal Winged Forest Guards. Since he feared opposition by slave-
owners to the loss of slaves, he provided inducements to the owners by promis-
ing them admission to the examinations, appointment to office. or increase in