鄭梉
In 1633 the Trịnh tried an amphibious assault on the Nguyễn to get around the wall. The Trịnh fleet was defeated by the Nguyễn fleet at the battle of Nhat-Le. Around 1635 the Trịnh copied the Nguyễn and sought military aid from the Europeans. Trịnh Tráng hired the Dutch to make cannons and ships for the Royal army. In 1642-43, the Trịnh army attacked the Nguyễn walls. With the aid of the Dutch cannons, the Trịnh army broke through the first wall but failed to break through the second. At sea, the Trịnh, with their Dutch ships "Kievit", "Nachtegaels" and "Woekende Book" were destroyed in a humiliating defeat by the Nguyễn fleet with their Chinese style galleys. Trịnh Tráng staged yet another offensive in 1648 but at the battle of Truong Duc, the Royal army was badly beaten by the Nguyễn. The new Lê king died around this time, perhaps as a result of the defeat. This now left the door open for the Nguyễn to finally go on the offensive.