Elite purges are an instrument of power control in authoritarian regimes. The purges in the Soviet Red Army during the 1937-38 Great Terror were one of the most intensive on record. Within two years, almost two thirds of the 1,863 oÿcers holding general-grade military ranks in 1936 were arrested; almost a half were executed. To analyze the patterns of repression among the Soviet high command, we compile a biographical data set from a large number of open and archival sources. Some of our findings should be familiar to historians: probability of being repressed was higher for certain ethnic minorities, higher ranks, and those with prior foreign contacts. Overall, our findings confirm that Stalin was not reacting to any imminent conspiracy threat but rather sought to preemptively minimize the risk of a possible coup. We show that Stalin specifically targeted the most competent oÿcers: controlling for other characteristics, including the military rank and party history, the probability of repression was much higher for younger cadres. Combined with the results that military promotions in 1941 were, other things equal, inversely related to age, this is the first systematic evidence that the Great Terror directly impacted the disastrous Red Army performance in the first years of the German invasion.