One of the Grand Administrators of Jiaozhi was Su Ding. In AD 39, two sisters Trưng Trắc and Trưng Nhị who were daughters of the Lac lord of Mê Linh, led an uprising that quickly spread to an area stretching approximate modern-day Vietnam (Jiaozhi, Jiuzhen, Hepu and Rinan), forcing Su Ding and the Han army to flee. All of Lac lords submitted to Trưng Trắc and crowned her Queen. In AD 42 the Han empire struck back by sending an reconquest expedition led by Ma Yuan. Copper columns of Ma Yuan was supposedly erected by Ma Yuan after he had suppressed the uprising of the Trưng Sisters in AD 44. Ma Yuan followed his conquest with a brutal course of assimilation, destroying the natives' bronze drums in order to build the column, on which the inscription "If this bronze column collapses, Jiaozhi will be destroyed" was carved, at the edge of the Chinese empire. Following the defeat of Trưng sisters, thousands of Chinese immigrants (mostly soldiers) arrived and settled in Jiaozhi, adopted surname Ma, and married with local Lac Viet girls, began the developing of Han-Viet ruling class while local Lac ruling-class families who had submitted to Ma Yuan were used as local functionaries in Han administration and were natural participants in the intermarriage process.