The Ming Emperor mobilized and dispatched a larger force under the general Li Rusong and Imperial Superintendent Song Yingchang. According to the collection of letters left by Song Yingchang, the strength of the Ming army was around 40,000, composed mostly of garrisons from the north, including around 3,000 men with experience against Japanese pirates under Qi Jiguang. Li wanted a winter campaign as the frozen ground would allow his artillery train to move more easily than it would under the roads turned into mud by the fall rains. At Uiju, King Sonjo and the Korean court formally welcomed Li and the other Chinese generals to Korea, where strategy was discussed. On January 5, Wu Weizhong leads 5,000 men across the Yalu River. Li Rusong's army of 35,000 reaches the Yalu River a few weeks later.