Imjin war was triggered by the Japanese invasion of Joseon in April 12, 1592 that lasted for 7 years until 1598. Though there was a temporary halt during the negotiation for ending the war, the Japanese army invaded again in January 1597 after the negotiations deteriorated. This re-invasion is often called the Jeongyujaeran.
The domestic and international background of Imjin War is that Japan waged the war on its mistaken conviction that it can win the war against Joseon easily with its superior military capability built over long civil war as part of efforts to expend the remaining military force in the wake of the unification of Japan while Joseon had relatively weaker military capability due to its fractional quarrels and arguments between parties
Splendid triumph of Admiral Yi Sun Shin in Imjin War!! (based on lunar calendar )