Can a civilian employee contracted Through the military be considered a commander/ chain of command?

https://www.goodreads.com/book/show/417640.A_Bright_Shining_Lie

He was civil service, not a contractor, at the time he commanded troops in the field in Vietnam, trust me, the book was very, very heavily documented....

I am unsure what this has to do with the Soldiers question? Thank you for your service.

CSM Darieus ZaGara - what Capt Daniel Goodman is referencing is LTC (RET) John Paul Vann who as an employee of USAID and became the Senior Advisor to ARVN II Corps. He was the equivalent to a Two Star General (like an SES now) that apparently had command authority of remaining US troops in 1972 when he died in a helicopter crash. My research has yet to turn up the authority he wielded command under but two different sources document this anomaly. His actions as the Senior Advisor were recognized with a posthumous Army DSC.

AR 600-20 has closed that door in para 1-5 where no civilian except the President has command authority.

I follow I do recall those aspects much appreciated....

Look at Tue link I just sent in, the only case I'd ever read of, during Vietnam, where that was apparently expressly not the case, I just sent it in as a separate link on this thread, honest, the only case I've ever read of where it was allowed, apparently because he was former Army, however, he commanded as a civilian, the book was quite explicit on that aspect, honest, I'd be most eager for your thoughts, or I you'd ever heard the story, many thanks, hope is of interest....

https://www.goodreads.com/book/show/417640.A_Bright_Shining_Lie

Here's the link again, just for convenience, about the life of John Paul Vann during Vietnam....

You left out Cabinet Secretaries. Secretary of the Army for instance. Top of all Army Chains of Command just under the POTUS.