The Wu family’s experiences illustrate in clear and human terms how institutions change over time. Far from lapsing into an ornamental or parasitic existence after the horrific purges of the Hongwu and Yongle reigns, merit nobles remained integral to the Ming dynasty. Reviewing the careers of the Wu men across the generations, we see their role change from field commanders, to a mix of field command and senior administration, and finally to exclusively capital administration. Rather than a caricatured image of corrupt irrelevance, merit nobles, properly considered, serve as a salutary reminder that military institutions, like other institutions, adapted to new circumstances. Examination of the Wu family yields a sharper understanding of who actually administered the dynasty’s core military institutions, what functions they served, and how they interacted with civil officials, palace eunuchs, officers, and the throne. Civil officials came and went, eunuchs held posts for longer, and military officers led campaigns, but merit nobles provided much of the continuity in personnel so essential for the operation of the Capital Training Divisions and Chief Military Commissions, pillars of the dynastic military.