鄭檢
However the Ming canceled their intervention. The struggle continued as with aided by members of two powerful Thanh Hóa military clans, the Nguyễn and Trịnh, the Lê family slowly made their way back to power. This effort continued through most of the sixteenth century, and in the course of the long seesaw struggle with the Mạc, a rivalry emerged between the two families, represented by their principal figures, Nguyễn Kim and Trịnh Kiểm (1503–1570). This tension developed even though the families were not merely allied militarily, but were also linked through marriage. Nguyễn Kim had married one of his daughters to Trịnh Kiểm, thus binding the two families in a time-honored fashion. Neither the military nor the marital connections, however, could forestall Trịnh Kiểm's personal ambitions. The ongoing contest for political supremacy gradually saw the Trịnh gain the upper hand, a position that was secured when the Nguyễn paterfamilias was murdered at the hands of a surrendering Mạc general in 1545. Eager to eliminate his rivals, Trịnh Kiểm arranged to have the elder Nguyễn son killed. His youngest son, Nguyễn Hoàng, saw in this act his own fate unless he took measures to protect himself. Through his sister, Kiểm's wife, Hoàng requested that he be appointed governor general of the distant southern frontier territories of Thuận Hoá and Quảng Nam. Remote exile of this political challenger suited the Trịnh overlord, and he agreed to the request. Shortly thereafter, in 1558, Nguyễn Hoàng entered the southern realms, marking the beginnings of a political division that would have lasted for 250 years.