In spite of the superiority of Japanese land forces, ultimately the two expeditions failed (though they did devastate the Korean landmass) from factors such as Korean naval superiority (which, led by Admiral Yi Sun-shin, harassed Japanese supply lines continuously throughout the wars, resulting in supply shortages on land), the commitment of sizeable Ming forces to Korea, Korean guerrilla actions, the underestimation of resistance by Japanese commanders (in the first campaign of 1592, Korean defenses on land were caught unprepared, under-trained, and under-armed; they were rapidly overrun, with only a limited number of successfully resistant engagements against the more-experienced and battle-hardened Japanese forces - in the second campaign of 1597, Korean and Ming forces proved to be a far more difficult challenge and, with the support of continued Korean naval superiority, limited Japanese gains to parts southeastern Korea), and wavering Japanese commitment to the campaigns as the wars dragged on.