Drawing on the upper-echelons theory and diversity issues, this study examines the relationships between top management team (TMT) organizational tenure, tenure diversity, and combat performance. The study is based on of Korea Combat Training Center (KCTC) that is designed for training and evaluation of the battalion combat power. Findings indicate that battalions with higher levels of TMT tenure have a positive effect on combat performance. Tenure diversity of TMT has a negative effect on combat performance. In addition, results showed that the negative relationships between tenure diversity of TMT and combat performance are attenuated by commander’s shared experience with other TMT members.