There has been some discussion on facebook and twitter about whether the new "crisis" in US civil-military relations concerning retired senior officers at the conventions is new or not. I have already written some about it--that this tension, not really a crisis, is inevitable given the competition among the parties making their own restraint irrational (that is, it is a poor strategy in a game theoretic sense) and that heaps of retired officers are available so surely a few will step out.
The difference this time, to be clear, I think, is that Flynn and Allen were major/featured speakers at the conventions, which is distinct from previous elections where the recruited retired officers mostly just signed joint letters of endorsement (or opposition, like this one I recently signed).
But I don't know, because I cannot recall really who appeared at which conventions (I watched more of these conventions than any other and I don't think I am alone in that) nor know which acts by politically active retired officers garnered criticism from active or retired officers or random experts. Indeed, one of things that is different this time around is that we have twitter/facebook/other social media in a much bigger way, so it is easy to get quick criticisms out there than ever before.
All this means: an enterprising graduate student interested in US civil-military relations could design a project that examines whether retired officers spoke at prior conventions, as well as other political activities, and also examines the reactions. It should not be that hard to develop plausible hypotheses for either side--that things have been mostly constant or that there are relatively new dynamics. The constant hypotheses would focus on things I mentioned before: the nature of party competition and the availability of officers as well as the norms of a professional military. For change? Perhaps more upset because some officers are endorsing the Democrat, which is a relatively new phenomenon (maybe) and this disturbs the largely conservative military more (H/T to NB/JF). Or perhaps the more batshit crazy the candidate and the officer, the more likely there is controversy--the Trump/Flynn hypothesis.
Anyhow, I don't have an answer for this as I just don't have a good sense of the change over time. Recency bias is a killer here, and the best weapon against recency bias is a fully armed and operational PhD student.