The ethnic composition of the Russian armed forces has been a source of popular speculation since the 2022 full-scale invasion of Ukraine. The literature suggests that in militaries where promotions occur on non-merit characteristics – such as ethnicity – a result can be lower morale, less information sharing, weaker cohesion, and ultimately inferior battlefield performance. Although studies of the “ethnic factor” in the imperial and Soviet armies abound, scholars lack microdata on the modern Russian military. Using a leaked dataset of information on almost 120,000 Russian service members, we show how ethnic inequalities and group hierarchies were reflected in the manpower of the Russian armed forces that invaded Ukraine in February 2022.