How did Kublai Khan defeat Song Jun step by step?

In March of the sixth year of Mongolian Yuan Dynasty (1269), the Mongols surrounded Fancheng again, and Song Jinghu took control of Zhang Shijie to lead the troops to rescue, but was defeated by the Soviet army in Chitanpu. In July, Xia Gui, the deputy envoy of the Song Dynasty along the Yangtze River, helped the boat by the surging Han River, and was badly hit by the Mongolian water army in Huweizhou. Fan, the deputy commander in front of the temple, was defeated by the reading army in Guanzitan with the support of the boatman.

Several unsuccessful aid attempts made the defenders in Xiangfan City in a more difficult situation. Mongolia sent Liu to build warships and practice the water army at the front line of Xiangfan; With Zhang Hongfan's proposal, the outer power grid of Xiangfan will be strengthened, and the land and water traffic between Xiangfan and other places will be cut off. Xiangyang satrap can only cross the Hanshui River by small fishing boat to spy on the military situation. Lv Wende, his brother, did not expect that he had brought such a great disaster to the court and his relatives because of his greed for small profits, and he was remorseful and died of poison and gangrene on his back.

After Lv Wende's death, the Southern Song Dynasty sent another messenger, Li Tingzhi, who was active in the fight against the Mongolian army in Huai River and Huai River, as Jinghu Ambassador, and continued to supervise the division to help Xiangfan. However, Jia Sidao was afraid of winning the battle and making contributions to himself, so he ordered his son-in-law and confidant Fan to restrain him and refused to listen to the constraints. Fan, relying on Jia Sidao, colluded with each other and played with prostitutes and concubines in the camp all day, not taking Xiangyang as a priority. He refused to send troops without a court order.

Without help, Lu Huan Wen had to lead more than 10,000 Xiangyang defenders to attack Wanshanbao in the west of Xiangyang. The result was defeated by the Mongolian army and forced to retreat into the city again. In the difficult situation of not seeing reinforcements in the Southern Song Dynasty, Xiang and Fan Junmin supported each other by using the pontoon bridge on the river, and * * * held on. They tore down houses for firewood, sewed banknotes for clothes, and were unswervingly determined to defend the city.