In April 1609, Satsuma Domain launched a second invasion of the Ryukyu Kingdom. Within a month, they conquered the Amami Islands in the face of fierce resistance on all but Okinoerabu Island. After Satsuma landed on Kouri Island, across from Unten Harbor, Ryukyu sent a thousand soldiers, commanded by Nago Ryōhō, to reinforce Nakijin Castle. On 30 April, Nago Ryōhō's force met the Satsuma army near Nakijin, but retreated after sustaining a 50% casualty rate; Nakijin was captured and razed and Shō Kokushi, the garrison commander and the heir to the Ryukyuan throne, died from wounds sustained in the battle. Satsuma landed in Yomitanzan unopposed on 3 May, advancing overland towards Shuri and by sea towards Naha. Ryukyu was able to stop and drive Satsuma away from Naha, but Satsuma was able to capture Urasoe Castle and cross the Taihei Bridge, surrounding Shuri Castle. After fierce resistance, Shuri fell on 6 May and King Shō Nei surrendered.