The “Duo You ding,” discovered in 1980 in Chang'an county, Shaanxi, contains a 270-graph inscription recording a major battle between Zhou and Xianyun chariotry. In addition to presenting a complete translation of the inscription, this paper attempts to specify the date of the events narrated. The argument is developed along three lines of inquiry. First, it is shown that personal names mentioned in the inscription require that the events took place shortly after the tenth year of King Xuan's reign (i.e., 818 B.C.). Second, evidence from other bronze inscriptions is adduced to show that there was fighting between the Zhou and Xianyun in the years 816-15, suggesting that the battle described in the “Duo You ding” may have been part of this larger warfare. Third, comparison of internal calendrical notations in the inscription with other evidence for the calendrical significance of Zhou victory celebrations not only confirms the first two conclusions but also allows the date to be specified as the tenth month of 816 B.C. Finally, all of this information is correlated to give a rough outline of the Zhou-Xianyun war and to suggest some of its historical significance.