Feel free to point out any errors.
Your comment, “The US military won their war in Vietnam” contains some truth, some tradition, and some error.
U.S. fighting men did win all, or most, of the major battles so in that sense the U.S. Army did “win”; but at a cost that was not sustainable.
I contend, in hindsight, the U.S. Army lost the war when U.S. Army generals agreed to fight a land war in Asia for 14 years using tactics that played to the long-term advantage of insurgent forces and the North Vietnamese. The tit-for-tat fighting resulted in 50,000 U.S. dead and 300,000 wounded.
It should have been predicted by the Army that these casualty rates would not be supported by the public for 20 years. And it wasn't.
The traditional view is that the military is subservient to civilian authority; that is the rule.
The other rule, less mentioned, is that U.S. military leaders have an absolute responsibility to advocate effective war fighting strategy to civilian leaders and if civilian leaders pursue disastrous national policies top military brass have an obligation to resign and explain their concerns to the public.
I don't remember a lot of generals resigning because they opposed the policies of Kennedy, Johnson, or Nixon. Maybe there were some.