Service Branches
Service branches are the armed services as enduring institutions: they persist across conflicts through budgets, training pipelines, procurement systems, and professional cultures [huntington1957].
Branches matter to command because they shape what can be done and how it will be understood. Joint operations are as much about negotiating institutional constraints as about coordinating capabilities.
References
[huntington1957] Samuel P. Huntington. (1957). The Soldier and the State: The Theory and Politics of Civil-Military Relations. Belknap Press of Harvard University Press.
[janowitz1960] Morris Janowitz. (1960). The Professional Soldier: A Social and Political Portrait. Free Press.