Cao Quy Stake Yard: By chance, people in Mai Dong village, Lien Khe commune, Thuy Nguyen district, Hai Phong discovered 2 ironwood stakes lying underground. After that, the authorities arrived and took samples to inspect the date. Historians Phan Dai Doan and Phan Huy Le said that Cao Quy stake yard was the place where Tran Hung Dao buried stakes to block the river’s gate, forcing the enemy to run to Bach Dang estuary. After that, the survey team came here to excavate and discovered 9 more wooden stakes. According to C14 inspection results, these stakes are from 1270-1430 AD. On November 22, 19, the excavated area was expanded to 950 square meters and as a result, with 3 holes, 27 more wooden stakes were discovered. At the same time, the archaeological team cooperated with the Hai Phong museum to study more about the river and the ancient wharf here. According to the information provided by the local people, about 30 years ago, the family of Mr. Tu, Mrs. Che pu village 3, Mai Dong village discovered 10 wooden stakes. and Mr. Do from village 7 also found 3 wooden stakes while working in the fields. Survey results and archaeological excavations in Lien Khe commune showed that: the stakes were distributed in the East-West direction, with a diameter of 26 – 46cm, on the stakes with muzzle used to tie the zipper. The stakes are not aligned and based on the dating shows, these wooden stakes can be arranged in battle stance in the 13th century. Initially, the Institute of Archeology stated that the above stake belonged to the 3rd Bach Dang battle (1288), to prevent the Nguyen Mong army from entering the Gia river area and Tran Quoc Tuan’s command area, forcing the army This follows Da Bac river into Bach Dang river. From there, falling into the pre-arranged stake of Tran Quoc Tuan, submerging the entire Nguyen Mong army into the Bach Dang river bed, completely ending the dream of invasion of the Nguyen Mong empire with the nation of Dai Viet.